Title Visual geometric properties in Chinese character processing: abehavioural and event-related potentialstudy

Author(s) Gao, Dingguo.; 高定國.

Citation

Issued Date 2003

URL http://hdl.handle.net/10722/36225

Rights The author retains all proprietary rights, (such as patent rights)and the right to use in future works.

Visual Geometric Properties in Chinese Character

Processing:

A Behavioural and Event-Related Potential Study

by

Gao Dingguo

A thesis submitted in partial fulfilment of the requirements for

the Degree of Doctor of Philosophy

at the University of Hong Kong

May 2003

Declaration

I declare that this thesis represents my own work, except where due

acknowledgement is made, and that it has not been previously included in a thesis,

dissertation or report submitted to this University or any other institutions for a

degree, diploma or other qualification.

Signed

Gao Dingguo

May 2003

Acknowledgements

First of all, I wish to acknowledge most humbly my indebtedness to Prof. Henry S. R.

Kao, my supervisor and mentor, for his encouragement, supervision and comments

during the past four years. I particularly value the daily discussions of Chinese

language and other issues in cognitive neuroscience studies of language with him

when I was in Hong Kong. My hope is that this study can somewhat provide an

empirical support to his psycho-geometric framework of Chinese reading and writing.

The results basically coincide with my hypotheses although some parts should be

tested or studied further in future.

Prof. Lin Chen generously provided me with a copy of all his work in topological

perception. The topological processing of Chinese characters in this study is based

on his theory that a primitive and general function of the visual system is the

perception of global topological properties. I was very much impressed by this

theory and decided to use it to study Chinese character processing. My current work

has benefited immeasurably from the thorough discussions with Prof. Chen when I

was in his Laboratory in Beijing as a visiting scholar in 1997 and 1998 respectively

and when he visited the University of Hong Kong during the last few years. I wish

to express my deep gratitude to him for all his help.

I sincerely thank Prof. Miao Danming and his colleagues, Drs. Liu Xufeng and Luo

Zengxue, and Ms. Wang Wei at the Fourth Military Medical University in Xi'an for

their kind assistance in recruiting subjects, collecting the behavioural and EEG data

and processing the imaging data. I in particular enjoyed the friendship that

developed during my stay there for conducting the experiments.

I would like to express my special thanks to Professor. Charles Perfetti, Dr. Li Hai

Tan and Dr. Zhou Xiaolin for their talks and presentations on Chinese language

research, and Ms. Chen Xuefeng for her assistance in collecting references and

bringing messages from my supervisor when I was not in Hong Kong.

I should acknowledge my admiration, affection and appreciation for my wife,

Ling-Hui, a computer scientist who not only gave me complete spiritual support over

the years, especially for her indulgence for my not helping with house work and the

endless pressure from our son Tian-Tian, a very active boy at his 14 months old when

I was writing the thesis, but also assisted in developing a database to analyse all the

Chinese characters in Chapter 3.

Finally, I am also indebted to the Graduate School, Chinese Language Cognitive

Science Research Centre, and the Department of Psychology of the University of

Hong Kong for the financial and physical support to the study.

Abstract of thesis entitled

Visual Geometric Properties in Chinese Character Processing:

A Behavioural and Event-Related Potential Study

submitted by

Gao Dingguo

for the degree of Doctor of Philosophy

at the University of Hong Kong

in May 2003

Chen (1982a, 1989) proposed a framework of visual perception based on the Klein

hierarchy of geometries (see Piaget, 1953) in which a primitive and general function

of the visual system is the perception of global topological properties and Kao (2000)

further developed a psycho-geometric theory of Chinese reading and writing on the

basis of Chen (1982a) and Ai (1948/1965) in which characters with balance, closure

and holes, linearity, centre of gravity, orientation, connectivity, symmetry, and

parallelism should be recognized and learned faster and/or more easily. The present

study investigated the effects of visual geometric processing in Chinese character

processing through a behavioural and event-related potential (ERP) approach

indicating some visual geometric properties facilitate the identification of Chinese

characters.

In Chapter 1, the author gives a brief introduction of Chinese characters and an

overview of the previous research related to the topic, and outlines the perspectives

what can be done in this thesis. In Chapter 2, the author defines topology,

symmetry, holes, and other geometrical features to be used in the thesis and discusses

the theories concerned. In Chapter 3, the author analyses the psycho-geometric

patterns of the most commonly used Chinese characters; he concludes that there is a

high density of holes, connectivity, linearity, balance and symmetry in these

characters. In Chapter 4, the results from two associated experiments exploring the

role of topological properties in identifying Chinese characters through a visual

matching task and a priming test are presented. The findings show a dissociation of

topology effects in which an effect was only found in Chinese characters with high

frequency in a visual matching paradigm and an effect was obtained in Chinese

characters with low frequency in a priming paradigm. In addition, no frequency

effect was found in both visual matching and priming tests. Chapter 5 is an account

of four relatively independent experiments conducted to show whether the

geometrical properties identified in Chapter 3 are the primitive factors to affect

Chinese character judgement in a lexical decision paradigm. Experiment 3a-d

revealed a symmetry effect, a closure effect and a structure effect but not a linearity

effect which was found only in Chinese characters with low frequency. In addition,

a significant frequency effect was found in all four conditions. Chapter 6 reports on

the results from two event-related potential experiments to show the association of

brain activation with topological and symmetrical processing of Chinese characters.

Experiment 4 replicated the results by the above behavioural studies and found an

early occurrence of ERPs in processing topological properties. Experiment 5 showed

a similar pattern of processing symmetric properties in the behavioural study. Some

brain patterns of processing geometric properties based on the time course of ERPs

have been found to be associated with the above processing, say, the topological and

symmetrical processing. Chapter 7 is a general discussion to integrate all the issues

in which a psycho-geometric theory and a holistic processing view have been

addressed in detail, and a summary of all the investigation and experiments done in

the thesis.

Contents

Declaration

Acknowledgements i

Table of contents iii

Chapter 1 Introduction 1

1.1 Chinese characters: A unique written language 1

1.2 What features determine the identification of a Chinese character .... 2

Chapter 2 Research background 6

2.1 What is topology 6

2.2 What is symmetry 8

2.3 What are connectivity, linearity, closure and structure 11

2.4 Objective and organisation of the dissertation 14

Chapter 3 Psycho-geometrical analysis of the commonly used Chinese

characters 17

3.1 Introduction 17

3.2 Method 19

3.3 Results 20

3.3.1 Structure of the Chinese Character 20

3.3.2 Frequency of Usage and Number of Strokes 21

3.3.3 Holes 23

3.3.4 Connectivity 24

3.3.5 Linearity 25

iii

3.3.6 Symmetry 25

3.3.7 Balance 27

3.4 Summary 27

Chapter 4 Topological processing of Chinese characters 29

4.1 Experiment 1 31

4.1.1 Method 31

4.1.2 Results 34

4.1.3 Discussion 36

4.2 Experiment 2 38

4.2.1 Method 38

4.2.2 Results 40

4.2.3 Discussion 41

Chapter 5 Psycho-geometrical processing of Chinese characters 43

5.1 Experiment 3a 44

5.1.1 Method 44

5.1.2 Results 46

5.2 Experiment 3b 48

5.2.1 Method 48

5.2.2 Results 50

5.3 Experiment 3c 52

5.3.1 Method ••••• 52

5.3.2 Results 54

IV

5.4 Experiment 3d 55

5.4.1 Method 56

5.4.2 Results 57

5.5 Discussion 59

Chapter 6 Topological and symmetrical processing of Chinese characters:

An event related potential study 63

6.1 Introduction 63

6.2 Experiment 4 64

6.2.1 Method 64

6.2.2 Results 66

6.2.2.1 Behavioural data 67

6.2.2.2 ERP data 67

6.2.3 Discussion 69

6.3 Experiment 5 71

6.3.1 Method 72

6.3.2 Results 74

6.3.2.1 Behavioural data 74

6.3.2.2 ERP data 75

6.3.3 Discussion 79

Chapter 7 General discussion and summary 81

7.1 Psycho-geometric theory of Chinese character reading 81

7.1.1 Chinese characters and the characters structuring 81

V

7.1.2 Principles of Chinese character writing 83

7.1.3 Effects of character geometricity on visual recognition 84

7.2 Topological perception and functional hierarchy in form

perception 88

7.3 The neural mechanism of geometric property processing:

Evidence in topology and symmetry 93

7.4 Present and future 94

7.4.1 Implications 94

7.4.2 Limitations 95

7.2.3 Present and future directions 95

7.5 Summary

References 101

Appendix A 117

Appendix B 118

Appendix C 118

Appendix D 119

Appendix E 120

Appendix F 121

Appendix G 122

Appendix H 123

Appendix I ••••• 133

Appendix J 134

CHAPTER 1

INTRODUCTION

1.1 CHINESE CHARACTERS: A UNIQUE WRITTEN LANGUAGE

The Chinese writing system is unique in the world. Written Chinese or Chinese

characters are different in many aspects from the alphabetic written language. First, each

character is composed of strokes that are arrayed vertically and horizontally, and

occupies almost the same space as others, while an alphabetic word usually consists of

horizontally distributed alphabets. Second, all Chinese characters are monosyllabic and

have no syllables that do not carry a meaning except for a few exceptions, e.g., #1-44

(kel1 dou3-tadpole) in which $$• and 44 do not mean anything but $1444 means tadpole.

More importantly, although there are many phonograms in the Chinese language, it is

difficult to orthographically spell out a character, regardless of the experience in

orthography and correctness of pronunciation. Thirdly, a Chinese character is usually

composed of a phonetic determinative (or phonetic radical) and a semantic

determinative. Semantic radicals in a Chinese character strongly imply the meaning and

classification. For instance, if a character has a radical (yu2-fish), it is almost certain

this object will be a kind of fish, an animal which is living under water, or something

related to a fish. Although there are word-stems in alphabetic words, it is more common

for a Chinese character to carry such a radical. Finally, Chinese characters comprise

geometric structures, such as holes, squares, straight and oblique lines, dots and curves.

According to a psycho-geometric framework (Kao, 2000), this construction should be

easy to attract your attention to focus on the presented Chinese character. For detailed

discussion of Chinese characters, please see Ann (1987), Boltz (1994), Hoosain (1991),

Wang (1973) and Zhou (1998).

1.2 WHAT FEATURES DETERMINE THE IDENTIFICATION

OF A CHINESE CHARACTER?

1.2.1 Previous Work in Chinese Character Processing

In the past two decades, psychologists and linguists had conducted studies on

how people identify Chinese characters or what factors influence the processing.

Much attention has been drawn to debate whether phonology or morphology

occurs earlier or whether Chinese character identification is different from that of

alphabetic words. For example, some researchers found the phonology of a

Chinese character is crucial to access its meaning representation (access to the

lexicon), and the phonology of a Chinese character is activated at a very early

stage or to some extent is processed automatically (Cheng and Shih, 1988;

Perfetti and Tan, 1998; Perfetti and Zhang, 1991, 1995; Tan, Hoosain, and Siok,

1996; Lam, Perfetti, and Bell, 1991; see a review by Perfetti, Liu & Tan, in press).

This view of phonology-plus-meaning process was challenged by a script-to-

meaning view of Chinese reading (Chen, Yung, & Ng, 1988; Hoosain, & Osgood,

1983; Tzeng, Hung, & Wang, 1977; Zhou, 1997) and a dual route model in which

either a visual or a phonological path leads to the activation of the meaning of a

word (Coltheart, 1978; Plaut, McClelland, Seidenberg & Patterson, 1996;

Seidenberg, 1985; Seidenberg & McClelland, 1989). However, few studies have

paid attention to other issues of Chinese characters, e.g., the visual form of a

character and perceptual features in recognising a character.

1.2.2 Previous Work for Geometry in Perception

Ai (1948/1965) argued in his book "Issues in Chinese characters" that characters

with symmetric, closed, and/or linear (horizontal and/or vertical lines) features or

with less than ten strokes are recognized more easily than those with other

configurations. Zeng's investigation on Chinese characters also echoed this view

(Zeng, 1983). Kao (2000) has further developed a psycho-geometrical theory of

reading and writing Chinese characters, in which characters with balance, closure

and holes, linearity, centre of gravity, orientation, connectivity, symmetry, and

parallelism should be recognized and learned faster and/or more easily.

In fact, some studies in visual perception have shown that physical properties of a

stimulus play an important role in visual identification, especially in a

tachistoscopic environment. Chen (1982a), for instance, found that the

topologically equivalent objects are more difficult to distinguish than the

topologically different counterparts and thus advanced a hypothesis of

topological perception in which a primitive and general function of the visual

system is the perception of global topological properties (Chen, 1985, 1989; Todd,

Chen, & Norman, 1998).

In addition, everyday experiences and much empirical evidence have also

indicated that symmetry, one of the geometric features that constitute a Chinese

character, is an important visual primitive and facilitates processing in vision.

Research, for example, has shown that the presence of symmetry in a pattern or

visual composition can be detected more quickly than its absence, and some types

of symmetry, such as bilateral symmetry, are more readily verifiable than others

(see, for instance, Ballesteros, Millar & Reales, 1998; Baylis & Driver, 1994;

Biederman, 1987; Bruce & Morgan, 1975; Koffka, 1935; Locher & Nodine, 1989;

Marr, 1982; Wenderoth, 1997). Attneave (1957) and Day (1968) also found

symmetrical shapes were judged less complex than asymmetrical shapes with the

same total number of turns (sides) by approximately one standard deviation unit.

From the above review, it is understandable that these geometric features may

affect the processing of a Chinese character, given the unique construction of

Chinese characters that can be visually defined as a geometric figure, and the

previous empirical evidence in perception.

1.2.3 The issues for processing Chinese character: From geometry view

Chinese characters are undoubtedly composed of geometrical figures, such as dot,

square and line. The questions arising from the above overview are:

• Given the Chinese characters' geometrical features, what is the mathematical

distribution of geometricity of the commonly used Chinese characters?

• Do topology, symmetry, linearity, closure and structure (form arrangement)

play a role in identifying a Chinese character? Further, is there any

dissociation among the conditions, e.g., frequency, tests, and presentation

time?

• What is the association between the cortex activation and the processing?

Could we physiologically and psychologically demonstrate this association?

CHAPTER 2

RESEARCH BACKGROUND

2.1 WHAT IS TOPOLOGY?

Topology, a geometry developed by a German mathematician, Felix Klein, in his lecture

of 'Erlangen Programme' in 1872, is intended to study those properties that an object

retains under deformation—specifically, bending, stretching and squeezing, but not

breaking, cutting or tearing, which is called topological transformations. 'Knotted' is

typically a topological concept because you cannot untie a knot in closed loop by

stretching or bending it. Thus a triangle is topologically equivalent to a circle but not to

a straight-line segment. Similarly, a solid cube made of modelling clay could be

deformed into a ball by kneading. It could not, however, be molded into a sold torus

(ring) unless a hole were bored through it or two surfaces were joined together. A solid

cube is therefore not equivalent to a finger ring. Topological equivalence is defined

based on the invariants, such as connectivity/separation, closure and holes, and inside

and outside distinctions under topological transformations. More precisely, if there are

given two geometric objects or sets of points and if some two-way transformation takes

each point p of each set into one and only one point p' of the other and if the

transformation is continuous in the sense that points close to p become points close to p

then the transformation is called a homeomoxphism and the two sets are said to be

topologically equivalent. In general, topology is the study of properties that remain

invariant under homeomorphisms.

However, the deformation concept has certain limitations. If two figures are given in

Euclidean 2-dimensional space, called2 ~ that is, the space of ordinary plane geometry—

and if one of them comprise a circle tangent internally to a larger circle and the other is

composed of two externally tangent circles, then a homeomorphism exists that

transforms one figure into the other and therefore the two figures are topologically

equivalent. However, one figure cannot be changed to the other by distortion in 2. It is

possible to turn one of the circles through 180° around the common tangent line as axis,

thus carrying it into 3-dimensional space 3, and effecting the deformation. The extra

dimension may or may not be available, depending on the conditions of the problem. An

internally tangent sphere in 3 could be continuously deformed to bring it to a position of

external tangency by a rotation in hypothetical 4-dimensional space 4, which might

present no difficulty mathematically but would be impossible to achieve or even

visualize in a physical application. The mathematical context may also prevent the use

of an additional dimension. In any case, the deformation concept is not used or needed

in defining topology. For a detailed understanding of topology, see Aleksandrov,

Kolmogorov and Lavrent'ev (1963).

Chen (1982a, 1985; Todd, Chen, & Norman, 1998) argued that a primitive and general

function of the visual system is the perception of global topological invariants.

Evidence for this hypothesis has been supported by the studies in apparent motion (Chen,

1985), 3D form discrimination (Todd, Chen & Norman, 1998), object-superiority effect

(Weisstein & Harris, 1974; McClelland, 1978; Williams & Weisstein, 1978; Chen,

1982b), grouping (Olson & Attneave, 1970; Pomerantz, Sager & Stoever, 1977; Chen,

1982c), card sorting (Palmer, 1978), effortless texture discrimination (Julesz, 1981),

visual sensitivity to distinction in topology (Pomerantz, 1980; Chen, 1982a) and

competitive organization with simultaneous factors (Chen, 1982d).

One of the objectives of the present study aimed to explore whether topological

properties affect processing Chinese characters, or whether the above hypothesis by

Chen (1982a) applies to Chinese character identification.

2.2 WHAT IS SYMMETRY?

The word 'symmetry' is used in our everyday language with two meanings. In one

sense, 'symmetry' means something like 'well-proportioned, well-balanced' and

'symmetry' denotes that sort of concordance of several parts by which they integrate

into a whole. In a word, beauty is associated with symmetry. In another sense,

'symmetry' can be mathematically defined. In fact, bilateral symmetry, the commonest

symmetry, is used more frequently.

Symmetry of an object is a transformation that leaves it apparently unchanged. The

number and type of such transformations depend on the geometry of the object to which

the transformations are applied. The meaning and variety of symmetry transformations

may be illustrated by considering a square lying on a table. In all patterns there are four

basic symmetry transformations or rigid motions: translation (rigid motion with

repetition along a line), reflection (rigid motion with repetition across an axis), glide

reflection (rigid motion with reflected repetition along a line), and rotation (rigid motion

with repetition around a point). A circle would be regarded to have higher symmetry

because, for instance, it could be rotated through an infinite number of angles (not just

multiples of 90 degrees) to give an identical circle.

In this study, we mainly focused on bilateral symmetry of Chinese characters. Bilateral

symmetry can be precisely defined as: A shape is bilaterally symmetric if there exists

some reflection that leaves it invariant - that is, unchanged in appearance. What is clear

is that a mathematically symmetrical object is not necessarily visually beautiful although

this is not generally taken note of, because this definition does not capture its aesthetic

aspects very well and imperfections that destroy mathematical symmetry may add

aesthetic value somehow (This issue will not be discussed in the study).

For Chinese characters, symmetry takes place through reflection and translation. Most

of the symmetric Chinese characters are of bilateral symmetry type. Some characters

are bilaterally symmetric through a vertical axis, e.g., (xinl-hot) and "H" (zai4-

again) and some through a horizontal one (The case can also be named as vertical

symmetry although it is a variation of bilateral symmetry), e.g., "HI" (po3-forbidden)

and "]=[" (ju4-large). However, symmetry in Chinese characters also appears through

translation, e.g., (lin2-forest) and "M" (peng2-friend). As described before,

symmetry is an important visual primitive and has been proved to facilitate processing

in visual perception (Attneave, 1957; Ballesteros, Millar & Reales, 1998; Baylis &

Driver, 1994; Biederman, 1987; Bruce & Morgan, 1975; Day, 1968; Koffka, 1935;

Locher & Nodine, 1973, 1989; Marr, 1982; Wenderoth, 1997). Given that a large

amount of Chinese characters are symmetric, it would be reasonable to hypothesise that

symmetry is a crucial and primitive feature in processing Chinese characters, especially

in the early stage of the process. Research, for example, has shown that the presence of

symmetry in a pattern or visual composition can be detected more quickly tb^ri its

absence, and some types of symmetry, such as bilateral, are more readily verifiable than

others (see, for instance, Ballesteros, Millar & Reales, 1998; Baylis & Driver, 1994;

Biederman, 1987; Bruce & Morgan, 1975; Koffka, 1935; Locher & Nodine, 1989; Marr,

1982; Troje & Buelthoff, 1998; Wenderoth, 1997). Furthermore, consideration on

symmetry has been drawn to an evolution theory in which preferences for symmetry

have evolved in animals because the degree of symmetry in signals indicates the

signaller's quality, and may arise as a by-product of the need to recognise objects

irrespective of their position and orientation in the visual field (Enquist & Arak, 1994).

This may account for the observed convergence on symmetrical forms in nature and

decorative art.

The second objective of the present study was to analyse a character through the

classification of symmetry, including near symmetry as it was hard to determine a

strictly mathematical symmetry in Chinese characters, and test whether symmetry would

facilitate processing symmetrical Chinese characters more quickly than asymmetrical or

near-symmetrical characters.

10

2.3 WHAT ARE CONNECTIVITY, LINEARITY, CLSOURE, AND

STRUCTURE?

Both Ai (1948/1965) and Kao (2000) argued that Chinese characters with symmetry,

closure, holes, centre of gravity, orientation, connectivity, parallelism and/or linear

(horizontal and/or vertical lines) features should be recognized more easily than those

with other configurations. Kao (2000) further developed a psycho-geometrical theory of

reading and writing Chinese characters based on the above consideration. According to

Kao (2000), central to the perceptual organization of the character form are some

properties underlying the visual-spatial structure of Chinese characters. The visual

frame can be analysed from the perceptual elements of shape, form, space, and balance.

On a more visual spatial level, several geometrical principles of visual perception are

pertinent to the cognitive map of the character produced in and by the act of reading.

These include connectivity, inside-outside distinctions, holes, co-linearity, orientation

and symmetry. Characters sharing these visual-spatial properties are predicted to

process more efficiently, say, faster or more accurately, than those characters sharing

less of these properties. A conceptual framework has been developed to describe the

highlights of the above observations within a systematic analysis of the components of

Chinese characters.

In this study, we selected a few salient features including connectivity, linearity, closure

and holes, and left-to-right or top-to-down structure to conduct our investigation.

11

2.3.1 Holes

A hole can be operationally defined as an entity consisting of a finite line (straight,

cursive or mixed) without an end point. One of the most apparent features of a hole is

closure which is seen as one of three fundamental properties of topological geometry

(the other two are connectivity and inside and outside relations, see Chen, 1989).

According to Chen (1982a, 1985) and Todd, Chen and Norman (1998), a primitive and

general function of the visual system is the perception of global topological properties

and the relative perceptual salience of object properties may be systematically related to

their structural stability under change, in a manner that is similar to the Klein hierarchy

of geometries. That is, the processing of topological feature is earlier than those of

Euclidean, affine and projective geometrical features. Piaget (1953) even found

topological ideas, which include proximity, separation, order, enclosure, and continuity,

developed earlier in children than the Euclidean. In fact, one of the methods to construct

a Chinese character is topological transformation under which two characters are

topologically equivalent (see Liu, 1993). A hole can centralize people's vision in a

frame and thus receives the most attention (Casati & Varzi, 1994). On the above studies,

it is assumed that there will be a superiority effect in perceiving, recognizing and

learning a Chinese character with hole(s) or with a closure structure.

2.3.2 Connectivity

Connectivity refers to an entity without separation. Objects connected with each other

would be more probable to be perceived as a whole according to Chen (1989) and

12

Koffka (1935). According to a topological processing view, whether an entity is

continuous or separated is very easy to judge. There are some Chinese characters with

the property of connectivity, e.g. " I " (wei4-protect) and "Hi" (mian4-face).

2.3.3 Linearity

In line with Ai's research (1948/1965), in this study Chinese characters consisting of

75% of straight lines or over, including horizontal or vertical such as "IE" (zheng4-

correct) and "^."(shengl- birth) were defined as having high linearity and those with

75% of curves or over, including dots and oblique lines such as "^"(cai3-exploit) and

"$£"(jiao3-cunning) as having low linearity. A Chinese character with high linearity is

supposed to be recognized more easily than a character with low linearity.

2.3.4 Closure

In the present study, closure means that a Chinese character is composed of a closed

frame which fully embeds other components of this character. 15 (wei2)-surround and

IS (guo2)-nation, for example, are typically structured with closure. A completely

closed Chinese character, e.g., "HI" (hui2-return), is quite different from " Jr]" (xiang4-

towards) in a topological view although they are morphologically similar.

2.3.5 Structure

13

Most of the Chinese characters are shaped with left-to-right, e.g., ttf (hao3-good) or top-

to-down structure, e.g., (wu4-must). As human vision is accustomed to search from

left-to-right instead of top-to-down (See Gazzaniga, 1998 and Marr, 1982 for an

introduction), it is reasonable to suppose that the characters with a 1 eft-to-right form

would be recognised better than other forms.

2.3.6 Brief Summary

While we have identified the visual primitives in Chinese characters, we should be

cautious in making any firm conclusion before further empirical evidence is given.

Chinese character identification is, after all, not a purely perceptual process. It may

involve phonological and semantic processes, and even affection and emotion. The

present study will try to avoid some distractions to work towards a dissociation of the

above visual properties through both a behavioural and a neuroimaging (ERP) approach.

2.4 OBJECTIVES OF THE STUDY AND ORGANISATION OF THE

DISSERTATION

2.4.1 Objectives of the Study

There are three main objectives in this study:

14

• To investigate the psycho-geometric features of the most commonly used Chinese

characters

• To examine whether topological properties affect Chinese character processing

through a behavioural and event related potential (ERP) approach

• To test whether symmetry, linearity, closure and left-to-right or top-to-down

structures influence Chinese character processing through a behavioural and ERP

approach

2.4.2 Organisation of the Dissertation

The dissertation is basically organised into seven chapters. In Chapter 1, the author

gives a brief introduction of the history of Chinese characters, provides an overview of

research related to the topic, and advances the perspectives what can be done in this

thesis. In Chapter 2, the author makes a detailed description of the definitions of

topology, symmetry, holes, and other geometrical features to be used in the dissertation

and discusses the theories concerned. He also states the objective of the thesis. In

Chapter 3, the author analyses the most commonly used Chinese characters in modern

Chinese language in a psycho-geometrical framework in which the author will select

structure, connectivity, holes and closure, linearity, balance and symmetry as indexes.

Chapter 4 reports on two associated experiments conducted to test whether topological

properties affect Chinese characters processing through a visual matching task and a

priming test. Chapter 5 reports on four relatively independent experiments carried out to

investigate whether the analysed geometrical properties in Chapter 3 are the primitive

15

factors to Chinese character judgement in a lexical decision paradigm. In Chapter 6,

the author presents the results from two event-related potential experiments to explore

the association of cortex activation with topological and symmetrical processing. In

Chapter 7, the author summarises all the investigation and experiments done in this

study and gives a general discussion.

16

CHAPTER 3

PSYCHO-GEOMETRIC ANALYSIS OF

THE COMMONLY USED CHINESE CHARACTERS

3.1 INTRODUCTION

Although there are almost one hundred thousand Chinese characters, which have been

used across different historical periods (see Wan & Hsia, 1957; Zhou, 1999), there are

only around 5,000 characters or fewer in active usage in modern Chinese (e.g., Ann

1986; Suen, 1986; Wang & Chang, 1986). According to Ann, 3,500 most frequently

used characters in Hong Kong cover 99.80% of the common usage of Chinese

characters. That is, a person would be able to read 99.80% of all the characters

contained in selected texts in a 1000-character article if she/he masters these 3500

characters. The finding was echoed on the Chinese mainland that 3,500 characters

occupy 99.87% of usage and with a skewed distribution on frequency of usage as

summarized in Table 1 (Wang & Chang, 1986).

Table 1

The skewed distribution of the frequency of usage of Chinese characters

Chinese characters (descending in frequency)

10 20 50 100 116 500 1000 1619 2000 3000 3156 3500 4000 4754

C.F. 15.85 23.10 35.08 47.70 50.24 79.76 91.37 96.60 98.07 99.63 99.73 99.87 99.96 100

Note: C. F. referred to cumulative frequency (%). (Source: Wang & Chang, 1986)

17

As a result, it is important to analyse the perceptual or orthographic features of these

commonly used Chinese characters in order to help people learn Chinese. A conceptual

framework developed by Kao (2000) was advanced to highlight the above observations

within a systematic analysis of the components in each Chinese character. The main

points in the psycho-geometric approach to Chinese character reading are presented

below.

At the body-character interface, some visual-spatial patterns are more salient or

important than others. They are those closely reflecting or conforming to basic

topological properties of visual perception. Fundamentally, a Chinese character should

be seen to portray an imaginary or visible rigid square, although modern forms may be

written within a rectangular shape. A square is the perfect geometric pattern as it

incorporates hole, linearity, symmetry, parallelism, connectivity and/or orientation. With

an implied correspondence between the shape of the square and the symbol, characters

may vary in terms of the extent to which they possess the geometric properties of the

square.

Cognitive changes associated with the geometric variations of the characters include

clerical speed and accuracy, spatial ability, abstract reasoning, digit span, short-term

memory, picture memory, and cognitive reaction time and accuracy.

Stylistic variations of Chinese characters reflect individualized forms of strokes

organization in the character. The patterns of geometricity in the character may include:

18

Shape, e.g., A (triangle), • (square), • (rectangle); size; balance (e.g., £?); closure and

holes (singular or plural, e.g., • , kou3 - mouth, @, mu4 - eye); linearity (e.g., IE,

zheng4 - right); centre of gravity (e.g., ®, hui2 - return); orientation (e.g., fjj, shanl -

mountain); connectivity (e.g., gongl - bow); symmetry (e.g., zu2 - soldier, H

men2- door); parallelity (e.g., H , er4- two, H , sanl- three); inside-outside distinctions

(e.g., @1, kun4 - trap vs. dail - retarded), and global and detailed figures.

The present investigation aimed to establish a database and analyse the most commonly

used Chinese characters in modern Chinese through a psycho-geometric approach (Kao,

2000).

3.2 METHOD

3.2.1 Source of the Selected Chinese Characters

A set of 4,575 most frequently used Chinese characters was extracted from 'A frequency

dictionary in modern Chinese' (Wang & Chang, 1986), which has been a widely cited

handbook in Chinese language research. These characters represented a total of

1,808,114 characters selected from: a) articles in politics, economy, philosophy, history,

military affairs and so on in popular newspapers, magazines and periodicals, b)

scientific articles which focus on the issues of daily life, c) spoken materials from drama,

libretto and scenario, commentaries, and songs, d) novels, essays and tales, and e)

articles from elementary and secondary school textbooks.

19

3.2.2 Data Collection and Analysis

All the data of the selected characters were compiled by Foxpro and processed by SPSS.

In the present investigation, only the structure, stroke, hole, connectivity, linearity,

symmetry and balance of a Chinese character were analysed.

3.3 RESULTS

3.3.1 Structure of the Chinese Character

Table 2 Distribution of different structures

Structure of the Chinese characters

a b c d e f g h l J

First 100 30 18 1 6 6 1 1 0 0 37

First 500 202 129 5 22 18 5 3 1 1 114

Total (4573) 2823 1028 23 192 117 45 33 14 6 293

Note: a, b, c, d, e, f, g, h, i, and j refers to the structure feature of a character.

According to Fu (1993), Chinese characters are basically classified into ten types in

structure, which were showed as follows: a) left-right (^fl - and), b) top-down ( ^ -

word), c) fully closed ( 0 - return), d) partially surrounded with roof and left flank (11 -

press), e) partly surrounded with floor and left flank (iH - arrival), f) partly surrounded

with roof and right flank ('rJ - sentence), g) surrounded without floor (|W] - same), h)

surrounded without right flank (Ee - great), i) surrounded without roof (!><! - violent), and

j) independent ( ^ - centre). Some researchers also roughly defined all the d, e, f, and g

20

structures as the partially surrounded. We found all the selected characters can be

categorized into the ten groups mentioned above (see Table 2).

The results revealed that over 60% of Chinese characters are of left-right structure,

around 20% of top-down and less than 20% of other structures. Although the first two

kinds of structures dominate the distribution, among the first 100 Chinese characters

descending in frequency and covering 51% of usage, the characters with independent

structures, in which most are connected in strokes, are of 37% (37 occurrences) and

among the first 500 characters which cover almost 70% of usage, 22.8% (114

occurrences in total) respectively.

3.3.2 Frequency of Usage and Number of Strokes

Loo (1989) found the frequency of characters, whether they are simplified or traditional,

is inversely proportional to the number of strokes. The more frequently the characters

are used, the fewer strokes they will have. This implies the simplification movement of

Chinese characters advocated in the Chinese mainland since the 1950's was reasonable.

In addition, simplified characters have around 22.50% fewer strokes than the traditional

form, which may translate into cost savings in the printing industries and time saving in

manual writing and facsimile transmission. However, the psychological or cognitive

effect with reference to this should be further investigated before a firm conclusion is

made. Simplification may have damaged the good form which existed in a traditional

Chinese character. For instance, the simplified form of ^ (chel-car) is asymmetric, less

21

parallel and linear comparing to its traditional form, i f . Cheng (1997) compared the

2173 simplified characters with the traditional counterparts and found a 1.8-stroke

savings per character on average in these simplified characters, indicating writing these

characters would save 1.8 hand movements per character. Simplification, however,

generates a number of visually similar characters and polysemies which would make

reading Chinese difficult.

Table 3

Correlation of Frequency and Stroke and Mean Strokes

High-frequency Mid-frequency Low-frequency Total

Pearson Correlation -0.196(1621) -0.129(1591) -0.011 (1362) -0.183 (4574)

Mean Strokes 8.66 (3.12) 10.59 (3.42) 11.45(3.69) 10.16(3.59)

Note: numbers in the brackets of the second row is the characters used; and the numbers in the brackets of the thirds row is the standard deviations.

Table 3 showed the correlation of frequency2 and stroke number. Interestingly, for low

frequency characters, almost no correlation existed between frequency and stroke

number, but the high and mid frequency parts did show some correlation (0.196 and

0.129 respectively and both reached a significant level, a = 0.05). This result coincided

with the skewed distribution of frequency of Chinese characters in which low frequency

characters were extremely rarely used and thus a low correlation was obtained.

Although at present it was premature to conclude whether simplified Chinese characters

are easier or more difficult to learn, this finding and the fact that simplified Chinese

characters were given official writing system status on the Chinese mainland and

Singapore suggested that simplified characters would at least not be inferior to

22

traditional Chinese characters currently used in Hong Kong, Macao and Taiwan. For

high frequency characters, there were about 2 strokes fewer than those with mid-

frequency or around 3 strokes fewer than those with low frequency characters. The

results were consistent with those in Loo's and Cheng's studies (Cheng, 1997; Loo,

1989).

3.3.3 Holes

Casati and Varzi (1994) believed that the way a hole can be filled receives the most

attention and undoubtedly holes play an important role in the organisation of visual

perception. Fu (1999) reported that out of 11,834 characters in total there are 20.34% of

Chinese characters consisting of the radical' P ' (kou3-mouth), which is typically a hole

and much more than other radicals or components. Holes are one of the most salient

topological properties (Casati & Varzi, 1994) and appear commonly in Chinese

characters. Table 4 showed the distribution of holes in Chinese characters.

Table 4

Holes in the selected Chinese characters

Number of Holes

1 10 11 12

HF

MF

LF

Total

662

522

417

1601

389

365

291

1045

265

278

281

824

139

191

141

471

110

146

118

374

36

47

65

148

14

28

21

63

4

8

17

29

1 5

5

11

1 0 1 0 2 2

4 2

Note: HF refers to high frequency, MF to mid-frequency and LF to low frequency.

Table 4 presented the holes in the total 4574 characters. It showed that 65% of

characters contain hole(s) ranging from 1 to 12, and among those with hole(s), most

23

consist of 1 or 2 holes, indicating most of the commonly used Chinese characters consist

of hole(s). The distributions of holes across frequency are 959 characters (59%) for high

frequency, 1,069 (67%)for mid-frequency and 945 (69%) for low frequency.

3.3.4 Connectivity

Table 5

Number of characters with connectivity

Order of the characters descending in frequency

100 200 300 500 1000 Total

Connected 33 62 88 116 167 275

HF 196

MF 54

LF 25

Disconnected 67 138 212 384 833 4299

HF 1425

MF 1537

LF 1337

Note: HF refers to high frequency, MF to mid-frequency and LF to low frequency.

It is known that connectivity is also one of the approaches to create a character. The

distribution of the connected characters was extremely skewed (see Table 5). Among

the first 300 characters, around 30% of them are connected and 71% of the connected

characters are of high frequency while only 6% of the totally selected 4575 characters

hold this feature, suggesting the most frequently used Chinese characters are connected.

As most of the connected characters are of du-ti-zi or the monosomatic, the results were

in fact consistent with the investigation for monosomatic characters (see also Table 2).

The results from these two investigations suggested that the connected Chinese

characters be easier to learn because the most frequently used characters might be the

24

easiest to read according to a principle of economy in learning. Again, further

behavioural and developmental evidence was needed.

3.3.5 Linearity

It is a fact that the most commonly used strokes in Chinese characters are straight lines.

Table 6 showed there are 260 characters with high linearity (75% lines or over in a

character) and 212 with low linearity (25% lines or less in a character). The results

indicated that both high and low linearity characters are not much common in the

frequently used Chinese characters. In addition, although no difference in linearity

across the frequency of the usage of characters was found, it might not apply to the case

of traditional Chinese characters as the simplification of Chinese characters might have

changed the linearity.

Table 6

Distribution of the selected Chinese characters across linearity

Linearity High-frequency Mid-frequency Low-frequency Total

High 115 76 69 260

Low 103 65 44 212

3.3.6 Symmetry

In the present study, I classified the Chinese characters as symmetric (bilaterally and

vertically), near-symmetric and asymmetric according to the definition of symmetry.

Near-symmetry means some part(s) are symmetric although the whole character is

25

asymmetric. It is hard to define a strictly mathematical symmetry in Chinese characters,

especially in those characters with low frequency. To illustrate, # (lin2-forest) is

bilaterally symmetric, [[6 (za3-bundle) is nearly symmetric, meaning one or more

components in a character are symmetric but the whole is asymmetric, and ^ (gai4-

beggar) is asymmetric.

Table 7

Distribution of symmetry in the selected Chinese characters

Bilateral symmetry Vertical symmetry Near-symmetry Asymmetry

High-frequency 172 5 505 939

Mid-frequency 81 5 518 987

Low-frequency 53 3 450 856

Total 306 13 1473 2782

Note: The data of some characters with both bilateral and vertical symmetries are only regarded as bilateral symmetry, such as " 0 " (sun).

The results from table 7 showed that around 7% of characters are fully symmetric (11%

among high frequency characters), 32% are nearly symmetric (31% among high

frequency) and 61% are asymmetric (58% among high frequency characters). In

addition, nearly symmetric or asymmetric characters are approximately equally

distributed across the frequency of usage. There exist some characters with both

bilateral and vertical symmetries. They are shown as follows: "—" (yil-one), "X"

(gonl-work), "cf3" (zhongl-centre), "-f-" (shi2-ten), " H " (sanl-three), " ® " (hui2-

return), (koul-mouth), " 0 " (ri4-sun), " g " (mu4-eye), "ffl" (tian2-field), " i "

(wang2-king), "]t[" (chuanl-river), (fengl-many), (shenl-claim), "El" (yue4-

say), "jtt" (sa4-thirty), "M" (e4-bad) and (feil-false). In fact, there are other cases

26

that a character contains more than one symmetry such as bilateral plus repeated

(through translation), e.g., "J | " (jingl-light), "pp" (pin3-quality), " i t " (chu4-stand), and

"M." (shuangl -double).

3.3.7 Balance

Ai (1948/1965) argued that if a character with left-right structure has 13 or more strokes

and the stroke difference between the two sides are over 10, the character should be

difficult to read and write. The author defined this feature as the balance of a Chinese

character. A character meeting Ai's definition would be named as having weak balance.

There are in total 86 characters of this type with 9 of high frequency, 31 of mid-

frequency and 46 of low frequency.

3.4 Summary

Over 60% of Chinese characters are of left-right structure, around 20% of top-down and

less than 20% of other structures. In general, the frequency of characters is inversely

proportional to the number of strokes, i.e., the more frequently the characters are used,

the fewer strokes they will have. However, for low frequency characters, almost no

correlation exists between frequency and stroke number. For high frequency characters,

27

they will be about two strokes fewer than those with mid-frequency or around three

strokes fewer than those with low frequency.

Most of the frequently used Chinese characters (65% in total) contain hole(s), with most

of them having 1 or 2 holes. No apparent difference is revealed in the distribution of

hole(s) across frequency (59% for high frequency, 67% for mid-frequency and 69% for

low frequency).

Only 6% of the characters are connected in construction but the distribution of this

property (characters with connectivity) is extremely skewed. Among the first 300

characters around 30% of them are connected and 71 % of the connected characters are

of high frequency, suggesting that the most frequently used Chinese characters are

connected.

There are 260 characters with high linearity and 212 with low linearity but this finding

may not apply to traditional Chinese characters. Thirty-nine percent of the characters

are fully or partially symmetric and most of the fully symmetric characters are of high

frequency. Partially symmetric or asymmetric characters are approximately equally

distributed across the frequency of usage. There exist some characters with two or more

symmetries. Moreover, there are 86 characters in total with weak balance, that is, 9 with

high frequency, 31 with mid-frequency and 46 with low frequency.

28

CHAPTER 4

TOPOLOGICAL PROCESSING OF

CHINESE CHARACTERS

The efficiency of visual identification for a matching pair increases when the items in

the pair are similar in some crucial perceptual features and decreases when the items in

the pair do not hold those features. Accordingly, if a prime is identical to a target in one

or more perceptual cues in a paradigm of priming effect, this primed stimulus should

produce a positive priming effect on the target (namely direct priming) and if a prime

contains no specified feature(s) of the target, there would be no positive priming effect

and a negative priming effect might even appear. In Experiment 1, we used

topologically equivalent Chinese character pairings to examine whether topological

properties affected the identification process in a visual-matching task. In Experiment 2,

we adopted a priming paradigm to test the same effect in Experiment 1 through a lexical

decision task.

One of the first results motivating the development of models of word recognition was

the frequency effect. Words that appear more often in written language are usually

recognised faster than words that occur rarely (e.g., Balota & Chumbley, 1984; Forster

& Chambers, 1973; Gao, Zhong & Zeng, 1995). The cause for this effect is assumed to

be the familiarity of a reader with the words. High frequency words have been

encountered more frequently and are thus processed more easily. The correspondence

29

of the number of times that a reader has been exposed to a word with counts from

written frequency norms, however, is far from perfect. Other variables including the

subjective familiarity with a word (Gemsbacher, 1984); Connine, Mullennix, Shernoff

& Yelens, 1990), the concreteness of a word (Bleassdale, 1987) or its contextual

availability (Schwanenflugel, 1991) are highly correlated with frequency and have been

shown to affect word recognition measures over and above frequency. In this study, we

incidentally tested the frequency effect of Chinese characters although it was not our

main purpose.

A visual matching task was considered susceptible to pre-lexical process and a lexical

decision task more sensitive to post-lexical decision and integration processes (cf.,

Balota, 1990, 1994). In the following experiments, I tested the hypotheses concerning

topology effects at both the pre-lexical and post-lexical stages, as well as frequency

effect.

30

4.1 EXPERIMENT 1

Experiment 1 aimed to determine whether topological property is crucial to identify the

Chinese characters in the primitive stage of processing, namely the topology effect. We

manipulated topological equivalence and frequency as independent variables while

controlling strokes and other features. Chen (1985) suggested that topological properties,

that is, closedness, separation and outside and inside relationships, are primitive to

perception. In Experiment 1, a very short presentation time (42.6 ms) plus an immediate

mask, which made the stimuli are extremely hard to be recognised, was given to avoid a

semantic or high cognitive process such as identifying a two-character pair.

4.1.1 Method

Participants. Twenty undergraduate students of the Fourth Military Medical University,

Xi'an, China, participated in the experiment. All were native Mandarin (Putonghua)

speakers and had normal or corrected-to-normal vision. Their ages ranged from 20 to 24

years and all were male.

Stimuli. On the principles of the topological equivalence and difference, i.e.,

holes/closure, e.g., 5 (shi2-stone)-fi (ji3-self), separation/connectivity, e.g., )L (er2-

child)--fc; (qil-seven), and inside-outside distinction, e.g., Wl (kun4-surround)-S (dail-

retard), 90 Chinese characters were chosen as stimuli, among which half were in high

frequency and another half in low frequency from the characters analysed in the

31

previous investigation (see Chapter 3 of this thesis). High frequency characters referred

to those with no fewer than 30 occurrences per million and low frequency characters

with fewer than 5 occurrences per million according to Modern Chinese frequency

dictionary (Wang and Chang, 1986). Three characters were in a group that matched each

other in strokes, frequency and other constructions, and varied only in topological

properties. For instance, (shi2-ten) (kou3 - mouth) and " I " (gongl

- work) were of a group in which and X were topologically equivalent (both were

connected) and • was topologically different from the other two because P included a

hole and the others comprised no hole (see Appendix A for all the stimuli). These three

characters were matched into 6 two-character pairs. That is, , " P - P " , " I - I " ,

" + - P " P - I " and among which the first three pairs (self-pairings) were

exactly paired with themselves, the fourth and fifth pairs were paired with topological

difference and the sixth was matched with topological equivalence. There were

altogether 15 groups in each frequency condition (high and low). That is, 30 pairs are

topologically different and 15 pairs topologically equivalent in each condition.

Therefore, totally 90 two-character pairs in total were used as the stimuli in the

experiment.

Design. It was a two-factor within-subjects design, in which reaction time and response

error were dependent variables and topological equivalence and frequency were

independent variables.

32

Procedure. A personal computer (Compaq PII 266) plus a screen (17 inches) with a

refresh rate of 14.2 ms was used to run this experiment. The Chinese characters were

presented tachistoscopically in white against a black background in a normal (Song) font

and each pair was shown once in the centre of the visual field. The task of participants

was to determine whether the form of the characters of a pair was exactly identical or

not, as quickly and correctly as possible. That is, with reference to the example of ,

"P", and "I", only the first three pairs, , "P-P", "I-I" , were identical and

the remaining pairs were different but no participants had been told these before and

after the experiments, they said they did not know this relationship. Each participant

was given 180 trials in total with 30 seconds rest after the first 90 trials.

The procedure was automatically monitored by STIM, a software developed by

Neuroscan to record reaction time and accuracy for each participant. Each pair was

arranged horizontally (left to right) with a distance of 5° between the centres of two

characters. Each character was of the same size and subtended 0.780 horizontally and

0.720 vertically. Before each trial, a small figure, ̂ was presented in the centre of the

visual field to check central fixation. The purpose of selecting this figure was to avoid a

topological equivalence between the fixation figure and the followed stimuli which

might produce an unexpected priming effect. The presentation time of the figure varied

from 800 ms to 1200 ms with a mean of 1000 ms and a standard deviation 100 ms to

inhibit a habituation. Then a stimulus pair was presented 42.6 ms both in the left and

right visual fields (same visual centre as the fixation), immediately replaced in the same

location by a mask which consisted of 60% white random dots. The pattern mask

33

occupied the same space as the stimuli and was presented for 28.4 ms. The fixation-

stimuli-mask pairings were presented in random order across the total 180 trials. Before

the testing, each participant was given clear instructions about the experiment (see

Appendix H) and then ample practice trials. Participants pressed the "1" button for

identical items and "4" button for different items with thumbs in a four-key board

developed by Neuroscan. To balance the habituation of hands, half of the participants

responded with left thumb for "1" and right thumb for "4", and the others reversed the

response pattern. Participants were tested individually in a dimly lit and quiet room, and

the whole experiment lasted approximately 10 minutes.

4.1.2 Results

One participant's data were eliminated because of high response errors in self-pairings

(86.67% for high frequency and 95.56% for low frequency respectively). Reactions

greater or less than 2.5 standard deviations were also excluded from the analysis and

only correct responses were accepted. The results were shown in Table 8. Topological

property (different or equivalent) is main variable in an analysis of variance (GLM-

repeated measures). The important results were that (a) topologically equivalent

Chinese characters with high frequency were more difficult to discriminate at a

tachistoscopical environment, whereas characters with low frequency showed no effects;

and (b) no frequency effects were found in both topologically equivalent and different

conditions.

34

The conclusions were supported by analyses of variance. A reliable topology effect for

high frequency characters was found for both reaction time (RT; F(l,18)=7.65,

MSE=\521,2A, p<0.05) and accuracy (F(l,18)=6.85, MSE=ll.ll, p<0.05), but there

were no significant topology effect for low frequency characters in both RT

(,F(1,18)=0.27, MSE=29S7.98, p>0.05), and accuracy (F(l,18)=0.05, MS!£=134.47,

p>0.05). No frequency effect was found in both topologically different (RT:

F(l,18)=0.85, MSE-S12J5, p>0.05; Accuracy: F(l,18)=1.85, MSE=106.92, /?>0.05)

and equivalent conditions (RT: F(l,18)=2.65, MS1£=4484.78, p>0.05; Accuracy:

F(l,18)=0.69, MS£=168.81,/»>0.05).

Table 8 Mean reaction time and accuracy for identifying topological equivalent or different characters (n=19)

High frequency Low frequency Different Different

D X , v 683.80+178.94 D r p / , 692.61 ±184.83 E T ( m S ) Equivalent R T ( m S > Equivalent

718.87 + 207.11 683.48 + 213.00

Different Different

A / 0 / N 74.91 ±17.23 A , 0 / . 70.35 ± 117.10 Accuracy (%) „ . < , Accuracy (%) ^ . J v y Equivalent y y Equivalent

67.72± 15.28 71.23 + 16.93 Note: the numbers in the table refer to mean plus or minus standard deviation.

Table 9 Mean reaction time and accuracy for frequency effects (n-19)

Equivalent Different High frequency High frequency

•Qrp / v 718.87±207.11 D T , v 683.80+178.94 RT (ms) t r ^ (ms) T -v Low frequency Low frequency

683.49 ±213.00 692.61 ±184.83

High frequency High frequency 67.22± 15.28 A , 0 / . • • 74.91 ±17.23

ccuracy( o) Low frequency ccuracy( o) Low frequency

71.23 ± 16.93 70.35± 17.10 Note: the numbers in the table refer to mean plus or minus standard deviation.

35

4.1.3 Discussion

The results of Experiment 1 revealed interesting effects in identifying topologically

equivalent or different Chinese character pairs.

First, only a topology effect for Chinese characters with high frequency was found;

identifying a topologically equivalent Chinese character pair with high frequency was

more difficult than identifying a topologically different pair. This result led to the

conclusion that topological properties did affect Chinese character processing, which

was consistent with the previous visual perception studies (e.g., Chen, 1982a, b, c, d;

Todd, Chen, Norman, 1998).

Second, this effect was not obtained for Chinese characters with low frequency. The

causes might be as follows, (a) Strokes of the Chinese characters with low frequency

(6.96 + 2.11) in the experiment were significantly greater than those of the characters

with high frequency (4.42 + 2.01), indicating the stimuli with low frequency had higher

complexity than the high frequency counterparts. As Chinese characters occupied same

spaces, it was reasonable to think that the higher in complexity, the smaller in size for

each component. This small size plus a tachistoscopical presentation would

undoubtedly put the Chinese characters with low frequency as a task with higher

difficulty. Particularly, when this difficulty reached some threshold, the stimuli would

be hard to recognise. In one word, the visibility for those Chinese characters with low

frequency damaged or diluted the effect. To match all the controlled variables,

36

unfortunately, it is almost impossible to collect so many low frequency characters which

have the same strokes as their high frequency counterparts, (b) Organisation in these

characters is more complicated than that in its high frequency counterparts as more

strokes constitute a character. The complicity of organisation confounded the factors

determining the response (see Chen, 1990). To avoid these two negative effects, it is

necessary to enlarge the size of Chinese characters and to simplify the organization of

the Chinese characters with low frequency in the future studies.

The results also failed to reveal a frequency effect for both topologically equivalent and

different Chinese characters. It might be caused by the tachistoscopical presentation

environment and less semantic involvement in the processing. As discussed by Ferstl &

d'Arcais (1999), frequency effect would be more likely to happen in a semantic process.

Unfortunately, the process involved in the identification intentionally diluted the

semantic involvements. Thus, it was reasonable to conclude it should not present a

frequency effect, although we should also be cautious before any further studies are

conducted.

37

4.2 EXPERIMENT 2

Experiment 2 was intended to replicate the topological effect found in Experiment 1

through other paradigms, which will extend its generality. The experiment was designed

through a typical priming paradigm in which a prime stimulus preceded with a target

stimulus. Priming refers to the fact that the time to respond to a word (the target) is

sometimes influenced when it is preceded by another usually morphologically,

phonologically or semantically related word (the prime). In this experiment the prime

and target were topologically related (cf. Roediger & McDermott, 1993). When a

topologically equivalent target was presented after a prime, it should induce a priming

effect whereas a topologically different target should not produce any effect or even

have a negative effect. This echoes the rationale in Experiment 1. In fact, Blaxton

(1989), Jacoby and Hayman (1987), and Madigan, McDowd and Murphy (1991)

reported a priming effect through matching typography. Roediger and McDermott

(1993) suggested in a lexical decision task that a prime and target occurring in close

temporal contiguity would be more probable to get a priming effect. In the present

experiment, there was no interval between the prime and the target to be sure of a salient

priming.

4.2.1 Method

Participants. Ten undergraduate students of the Fourth Military Medical University,

Xi'an, China, participated in Experiment 2. All were native Mandarin (Putonghua)

38

speakers and had normal or corrected-to-normal vision. Their ages ranged from 20 to 24

years and all were male.

Stimuli. The stimuli were the same as those used in Experiment 1 (see Appendix A).

Sixty pseudo-Chinese characters3 were selected from Appendix G.

Design^ It was a two-factor within-subjects design, in which reaction time and response

error were dependent variables and the topological property of the prime was the

independent variable in a lexical decision test.

Procedure. The computer in Experiment 1 with the same configuration was used to run

this experiment. The experimental paradigm was as follows. After a fixation check, a

prime would be presented followed by a target and then a mask. The prime would be

either topological equivalent to or different from the followed target or bear no

relationship to the target (Chinese character vs. pseudo-Chinese character). The stimuli

(Chinese characters or pseudo-characters) were presented tachistoscopically in white

against a black background in a normal (Song) font and each pair (fixation-prime-target-

mask) was shown once in the centre of the visual field. The task of participants was to

determine whether the second presented character was a real Chinese character or a

pseudo-Chinese character (lexical decision) as quickly and as correctly as possible.

Each participant was given 120 trials in total with 30 seconds rest after the first 60 trials.

Half trials were used to judge real Chinese characters and another half to judge pseudo

Chinese characters.

39

The procedure was automatically monitored by STIM to record reaction times and

accurate responses for each participant. Each character was of the same size and

subtended 0.78 0 horizontally and 0.72 0 vertically. Before each trial, a small figure was

presented in the centre of the visual field to check central fixation. The presentation

time of the figure varied from 800 ms to 1200 ms with a mean of 1000 ms and a

standard deviation 100 ms to avoid a habituation. Then a prime was presented for 42.6

ms, replaced with no break in the same location by a target (real or pseudo Chinese

character) for 85.2 ms, followed immediately by a mask that consisted of 60% white

random dots. The pattern mask occupied the same space as the stimuli and was

presented for 28.4 ms. The fixation-prime-target-mask pairings were presented in

random order across the total 120 trials. Before the task, each participant was given

clear instructions about the experiment (see Appendix H) and then ample practice trials.

Participants pressed the "1" button for a real Chinese character and the "4" button for a

pseudo Chinese character with thumbs. To balance the habituation of hands, half of the

participants responded with the left thumb for "1" and the right thumb for "4", and the

others reversed the response pattern. Participants were tested individually in a dimly lit

and quiet room, and the whole experiment lasted approximately 7 minutes.

4.2.2 Results

Reactions greater or less than 2.5 standard deviations were excluded from the analysis

and only correct responses were accepted. The results are shown in Table 10. There

40

were main priming effects of topological property for low frequency characters in both

RT (F(l,9)=7.01, MSE=36l 1.48, /?<0.05) and accuracy (F(l, 9)=8.68, MSE-S2.96,

p<0.05), but there were no significant effects for high frequency characters in both RT

(F(l,9)=0.08, MS£= 1882.99,/»0.05) and accuracy (F(l,9)=0.31, MSE=l 14.57, p>0.05).

No frequency effects were found in both different (RT: F(l,18)=0.85, MSE=872.75,

p>0.05; Accuracy: F(l,18)=1.85, MSE=106.92,p>0.05) and equivalent conditions (RT:

F(l,18)=2.65, MSE=4484.78,p>0.05; Accuracy: F(l,18)=0.69, MSE=l6&M,p>0.05).

Table 10 Mean reaction time and accuracy for identifying real Chinese characters or pseudo Chinese characters (n—10)

High frequency Low frequency

RT (ms)

Accuracy (%)

Equivalent 658.31 ±179.71

Different 652.93 + 135.72

Equivalent 84.00+12.26

Different 86.67 + 9.94

RT (ms)

Accuracy (%)

Equivalent 734.77 + 144.83

Different 805.92 + 178.09

Equivalent 70.67 + 13.41

Different 58.67± 15.96

Note: the numbers in the table refer to mean plus or minus standard deviation.

4.2.3 Discussion

A reliable priming effect was obtained both in reaction time and accuracy for low

frequency Chinese characters but not for high frequency ones. The results were just

reversed to those in Experiment 1. However, the results were consistent with other

studies in implicit memory (MacLeod, 1989; Scarborough, Cortese & Scarborough,

1977). In fact, it was understandable to conclude that high frequency of stimuli

41

damaged the priming effect because it was not easy to induce a data-driven or perceptual

process, comparing to low frequency.

Again, no frequency effect was found through a lexical decision task. The interpretation

for this result was similar to that in Experiment 1, that is, a process which involved data-

driven processing would not show a frequency effect easily(Ferstl & d'Arcais, 1999).

42

Chapter 5

PSYCHO-GEOMETRIC PROCESSING OF

CHINESE CHARACTERS

Experiments 1 and 2 investigated whether topological properties in a Chinese character

would affect the processing. The findings show a dissociation of topology effects in

which an effect was only found in Chinese characters with high frequency in a visual

matching paradigm and an effect was obtained in Chinese characters with low frequency

in a priming paradigm. In addition, no frequency effect was found in both visual

matching and priming tests. As analysed in Chapter 3, Chinese characters also have

symmetrical, closed, and/or linear properties. According to Ai (1948/1965), these

Chinese characters should be recognised more easily than others. Kao (2000) further

developed a psycho-geometric framework of reading and writing Chinese characters.

Based on the previous analysis (see Chapter 3), the following experiments were used to

test this hypothesis that a character having symmetrical, connected, closed and/or linear

properties is processed more quickly or more accurately than those having not sharing

these properties. In this experiment, I adopted a lexical decision paradigm. This

paradigm is considered to use less semantic processing and therefore is an appropriate

programme to test whether these properties are the main factors to influence the Chinese

character processing. In fact, a priming task is aimed to induce a data-driven

processing, so does the lexical decision task. In experiments 3a-d, I used the latter

43

because it is easier to design a lexical decision task and to control other unexpected

variables.

5.1 EXPERIMENT 3a

Experiment 3 a aimed to determine whether symmetrical Chinese characters are

identified more easily than asymmetrical ones (Ai, 1948; Kao, 2000 and Zeng, 1983).

Previous research in other fields has proved the superiority effect of symmetry, namely

the symmetry effect (see also Chapter 2 and 3). In the present study, we continued to

adopt a lexical decision task to test the hypothesis.

5.1.1 Method

Participants. Participants were the same as those in Experiment 1.

Stimuli. On the basis of the symmetrical property of a Chinese character, forty

symmetrical Chinese characters and forty asymmetrical Chinese characters matching in

strokes, linearity, connectivity, closure and structure in each frequency condition, and

sixty-five pseudo-Chinese characters were adopted as stimuli. Of the real Chinese

characters, half were high frequency characters and half were low frequency characters.

For example, (da4- big) and (feil-false) are symmetrical samples of

high frequency characters and " ¥ " (han4-rare) and " " (jingl-capital) are

asymmetrical samples of low frequency characters (see Appendix B). The pseudo

44

characters were created according to the Chinese character orthography (see Appendix

G). From Appendix B, it was understood that a small amount of low frequency Chinese

characters are of near symmetry such as E® (qu4- cricket) due to a difficulty to find so

much completely asymmetrical Chinese characters with low frequency.

Design. It was a two-factor within-subjects lexical decision task, in which reaction time

and response accuracy were dependent variables and symmetry of the presented Chinese

characters and frequency were independent variables.

Procedure. The computer in Experiment 1 with the same configurations was used to run

this experiment. The experimental paradigm was that after a fixation, a character would

be presented at the same location of the fixation, followed by a mask which was

comprised of 60% random white dots against a black background. The character would

be either a symmetrical, asymmetrical or pseudo Chinese character. The characters

were presented tachistoscopically in white against a black background in a normal (Song)

font and each pair was shown once in the centre of the visual field. The task of the

participants was to determine whether the presented character was a real Chinese

character or a pseudo-Chinese character as quickly and as correctly as possible. Each

participant was given 145 trials in total with 30 seconds rest after the first 80 trials.

Fifty-five percent trials were used to judge real Chinese characters and the remaining

45% to identify pseudo Chinese characters, but no participants were told of this

arrangement before and after the test.

45

The procedure was automatically monitored by STIM to record reaction times and

accurate responses for each participant. Each character was of the same size and

subtended 0.78 0 horizontally and 0.72 0 vertically. Before each trial, the same figure

used in Experiment 1 was presented in the centre of the visual field to check central

fixation. The presentation time of the figure varied from 800 ms to 1200 ms with a

mean of 1000 ms and a standard deviation 100 ms to avoid a habituation. Then a

character was presented for 85.2 ms, immediately replaced in the same location by a

mask for 28.4 ms. The fixation-target-mask pairings were presented in random order

across the total 145 trials. Before the task, each participant was given a clear instruction

of the experiment (see Appendix H) and then ample practice trials. Participants pressed

the "1" button for a real Chinese character and the "4" button for a pseudo character

with thumbs. To balance the habituation of hands, half of the participants responded

with the left thumb for "1" and the right thumb for "4", and others reversed the response

pattern. Participants were tested individually in a dimly lit and quiet room, and the

whole experiment lasted approximately 8 minutes.

5.1.2 Results

Two participants' data were eliminated because of high response errors in low frequency

characters (80% and 60% for symmetric characters, and 85% and 85% for asymmetric

characters, respectively). Reactions greater or less than 2.5 standard deviations were

excluded from the analysis and only correct responses were accepted.

46

The results were shown in Table 11. Symmetric property (symmetry or asymmetry) of a

Chinese character and frequency were main variables in an analysis of variance (GLM-

repeated measures). There was a significant symmetry effect for low frequency

characters in both RT (F( 1,17)= 10.22, MS£=982.71, pO.Ol) and accuracy

(F(l,17)=5.47, MSE-IA6.9Q, p<0.05), but there were no significant effects for high

frequency characters in both RT (F(l,17)=3.94, MSF=446.72, ^>0.05), and accuracy

(F( 1,17)=0.68, MSE=50.20, p>0.05).

There was a significant frequency effect (Table 12) in both symmetric (RT:

F(l,17)=53.40, MS!£=1412.22, /K0.001; Accuracy: F(l,17)=37.99, MSE=82.07,

p<0.001) and asymmetric conditions (RT: F(l,17)=56.78, MSE=3059.54, ^<0.001;

Accuracy: F(l,17)=54.54, MSF^MS.SS^O.OOl).

Table 11 Mean reaction time and accuracy for identifying real Chinese characters or pseudo characters (n=18)

High frequency Low frequency Symmetric Symmetric

P T r m > 574.13 + 128.82 - 665.67+164.87 R1 (ms) A RT (ms)

Asymmetnc Asymmetnc 560.15 + 127.58 699.08 ± 186.87

Symmetric Symmetric . , 0 / , 87.22 + 10.03 . 68.61 ±12.10

Accuracy (%) . ^ . Accuracy (%) . Asymmetnc Asymmetnc

89.17 + 9.89 59.17± 15.74 Note: the numbers in the table refer to mean plus or minus standard deviation.

Table 12 Mean reaction time and accuracy for frequency effect (n-18)

Symmetric Asymmetric High frequency High frequency

, 574.13±127.87 D T , , 560.15± 127.59 RT (ms) T xl RT (ms) T „ v ' Low frequency Low frequency

665.67± 164.87 699.08 ± 186.87

47

High frequency High frequency

/ 0 / , 87.22± 10.03 . , 0 / . 89.17 + 9.89 Accuracy (%) T ~ Accuracy (%) T ~ J Low frequency J y Low frequency

68.61 + 12.10 59.17± 15.74 Note: the numbers in the table refer to mean plus or minus standard deviation.

5.2 EXPERIMENT 3b

Experiment 3b aimed to test whether linear Chinese characters, which had been

operationally defined in Chapter 3, were recognised better than non-linear ones. Ai

(1948/1965) and Kao (2000) had suggested a superiority effect of linearity, namely the

linearity effect (see also Chapter 2 and 3 of this dissertation). In this experiment, we

continued to adopt a lexical decision task, as used in Experiment 3 a, to test the above

hypothesis.

5.2.1 Method

Participants. Participants in the experiment were the same as those in Experiment 1.

Stimuli. On the basis of the linear property of a Chinese character, 22 linear Chinese

characters and 22 non-linear Chinese characters matching in strokes, symmetry, closure,

connectivity and structure in each frequency condition, and 36 pseudo characters were

selected as stimuli. Of the real Chinese characters, half were high frequency characters

and half were low frequency characters. A linear character referred to a character

consisting of more than 75% of straight lines (horizontal or vertical such as "IE"

48

(zheng4-correct) and (shengl-alive)) and a non-linear character meant it comprised

over 75% of curves including dot and oblique line such as (xiangl - home) and

"ffi" (lu4 - kill). All the selected Chinese characters were listed in Appendix C. The

pseudo characters were selected from Appendix G.

Design. It was a two-factor within-subjects lexical decision task, in which reaction time

and response accuracy were dependent variables and linearity of the presented Chinese

characters and frequency were independent variables.

Procedure. The whole procedure, including the fixation, stimuli and mask presentation

time, size and place, and task, was the same as that in Experiment 3 a, except for the

stimuli and trials. Each participant was given 80 trials in total with a 30-second rest

after the first 40 trials. Fifty-five percent trials were used to judge real Chinese

characters and the remaining 45% to identify pseudo Chinese characters, but no

participants were told of this arrangement before and after the test.

The procedure was automatically monitored by STIM to record reaction times and

accurate responses for each participant. Before the task, each participant was given

clear instructions about the experiment (see Appendix H) and then ample practice trials.

Participants pressed the "1" button for a real Chinese character and the "4" button for a

pseudo character with thumbs. To balance the habituation of hands, half of the

participants responded with the left thumb for "1" and the right thumb for "4", and

49

others reversed the response pattern. Participants were tested individually in a dimly lit

and quiet room, and the whole experiment lasted approximately 6 minutes.

5.2.2 Results

Three participants' data were eliminated because of high response errors in low

frequency non-linear characters (90.91% for all three participants). Reactions greater or

less than 2.5 standard deviations were excluded from the analysis and only correct

responses were accepted.

The results are shown in Table 13. The linear property (linear or non-linear) of a

Chinese character was of main variable in an analysis of variance (GLM-repeated

measures). There was no significant linearity effect for both high (RT: JP(1,16)=0.18,

MSE= 1570.56, p>0.05, and accuracy: F(l,16)=0.41, MSE=95.11, p>0.05) and low

frequency Chinese characters (RT: F(l,16)=1.33, MSE=\ 1601.27,/?>0.05, and accuracy:

F( 1,16)=2.95, MSE= 161.34, p>0.05).

There was also a significant frequency effect (Table 14) in both linear (RT:

F(l,16)=15.85, MSE=8364.09, ^<0.001; Accuracy: F(l,16)=47.80, MS£=221.50,

p<0.001) and non-linear conditions (RT: F(l,17)=23.33, JWS£'=10938.88, £><0.001;

Accuracy: F(l,17)=135.69, MSE=l26A0,p<0.00l).

Table 13 Mean reaction time and accuracy for identifying real Chinese characters or pseudo characters (n=17)

50

High frequency Low frequency

RT (ms)

Linear 560.98±99.67

Nonlinear 555.29± 130.09

RT (ms)

Linear 685.86 ± 207.31

Nonlinear 728.51 ±226.78

Accuracy (%)

Linear 86.10± 14.77

Nonlinear 88.24± 11.48

Accuracy (%)

Linear 50.80±21.58

Nonlinear 43.22± 14.56

Note: the numbers in the table refer to mean plus or minus standard deviation.

Table 14 Mean reaction time and accuracy for frequency effect (nz -18)

Linear Nonlinear

RT (ms)

High frequency 560,98±99.67

Low frequency 685.86 ± 207.31

RT (ms)

High frequency 555.25 ±130.09

Low frequency 728.51 ±226.78

Accuracy (%)

High frequency 86.10 ± 14.77

Low frequency 50.80 ± 21.58

Accuracy (%)

High frequency 88.24 ± 11.48

Low frequency 43.32 ±14.56

Low frequency

Accuracy (%) Nonlinear

88.24+11.48

RT (ms)

Accuracy (%)

Linear 685.86 + 207.31

Nonlinear 728.51 ±226.78

Linear 50.80+21.58

Nonlinear 43.22+14.56

Note: the numbers in the table refer to mean plus or minus standard deviation.

Table 14 Mean reaction time and accuracy for frequency effect (n-18)

Linear Nonlinear

RT (ms)

Accuracy (%)

High frequency 560,98±99.67

Low frequency 685.86 + 207.31

High frequency 86.10+14.77

Low frequency 50.80 + 21.58

RT (ms)

Accuracy (%)

High frequency 555.25 ±130.09

Low frequency 728.51 ±226.78

High frequency 88.24 ± 11.48

Low frequency 43.32 ±14.56

Note: the numbers in the table refer to mean plus or minus standard deviation.

51

5.3 EXPERIMENT 3c

Experiment 3c aimed to test whether the closed Chinese characters were recognised

faster or more accurately than opened or half-closed ones. Kao (2000) suggested a

superiority effect of closedness, say the closure effect (see Chapter 2 and 3). In this

experiment, we continued to adopt a lexical decision task, as used in Experiment 3a, to

test the hypothesis.

5.3.1 Method

Participants. Participants in the experiment were the same as those in Experiment 1.

Stimuli. On the basis of closure property of a Chinese character, 22 completely closed,

22 completely open, 22 half-open Chinese characters, matching in strokes, linearity,

connectivity, symmetry and structure in each frequency condition, and 54 pseudo

characters were selected as stimuli. Of the Chinese characters, half were high frequency

characters and half were low frequency characters in all three conditions. In the

experiment, a completely closed character was embedded in a closed frame, e.g., "15"

(nation) and " 0 " (prisoner), a completely open character was composed of no bound

frame, e.g., "iS" (state) and "jr"(celery), and a half-open character consisted of an

almost closed bound frame, e.g., "fE3" (depressed) and "f*|" (a Chinese surname). All

52

the selected Chinese characters were listed in Appendix D. The pseudo characters were

created according to the Chinese character orthography (see Appendix G).

Design. It was a two-factor within-subjects lexical decision task, in which reaction time

and accurate response were dependent variables and closedness of the presented Chinese

characters and frequency were independent variables.

Procedure. The whole procedure including the fixation, stimuli and mask presentation

time, size and place, and task was the same as that in Experiment 3a, except for the

stimuli and trials. Each participant was given 120 trials in total with 30 seconds rest

after every 60 trials. Fifty-five percent trials were used to judge real Chinese characters

and the remaining 45% to identify pseudo Chinese characters, but no participants were

told of this arrangement before and after the test.

The procedure was automatically monitored by STIM to record reaction times and

accurate responses for each participant. Before the task, each participant was given

clear instructions about the experiment (see Appendix H) and then ample practice trials.

Participants pressed the "1" button for a real Chinese character and the "4" button for a

pseudo character with thumbs. To balance the habituation of hands, half of the

participants responded with the left thumb for "1" and the right thumb for "4", and

others reversed the response pattern. Participants were tested individually in a dimly lit

room, and the whole experiment lasted approximately 6 minutes. The reaction times

and accuracy rates were recorded for each participant.

53

5.3.2 Results

Three participants' data were eliminated because of high response errors of completely

open characters for low frequency (over 90% for all three participants). Reactions

greater or less than 2.5 standard deviations were excluded from the analysis and only

correct responses were accepted.

The results were shown in Table 15. Closure property (completely closed, completely

open and half-closed) of a Chinese character was the main variable in an analysis of

variance (GLM-repeated measures). There was a significant effect of closure property

for low frequency characters (RT: F(2,32)=1.36, MSFK3885.04, /?>0.05, and accuracy:

F(2,32)=4.75, MSE=2S2.77, p<0.05) but there was no reliable effect for high frequency

characters (RT: F(2,32)=0.72, MS£=3724.52, p>0.05, and accuracy: F(2,32)=3.18,

MSE=\ 10.60, p=0.06). Post Hoc Test (LSD) showed a significant difference between

completely closed and half-closed characters (Diff=\7.65, SE=6.22, p<0.01).

There was a significant frequency effect (Table 16) in completely closed (RT:

F(l,16)=3.48, MSE=5722.07, p=0.08; Accuracy: F(l,16)=l 1.73, MSE=140.07,/K0.01),

and completely open (RT: F( 1,16)= 18.02, MSE=2642.18, p<0.001; Accuracy:

F(l,16)=51.31, MS£=148.58, p<0.001), and half-closed (RT: F(l,16)=13.87,

MSE=5775.09,p<0.0\; Accuracy: F(l,16)=53.52, MS£=203.88,p<0.001) conditions.

Table 15

54

Mean reaction time and accuracy for identifying real Chinese characters or pseudo characters (n~17)

High frequency Low frequency

RT (ms)

Completely closed 559.62 ± 136.10

Completely open 535.14+114.36

Half-closed 542.33 + 137.69

RT (ms)

Completely closed 608.01 ±170.83

Completely open 609.98± 161.16

Half-closed 639.42± 191.75

Accuracy (%)

Completely closed 79.68 ±13.84

Completely open 88.77 ± 11.82

Half-closed 83.96± 15.92

Accuracy (%)

Completely closed 65.78± 16.86

Completely open 58.82± 19.32

Half-closed 48.13 ± 18-11

Note: the numbers in the table refer to mean plus or minus standard deviation.

Table 16 Mean reaction time and accuracy for frequency effect (n=17)

Completely Closed Completely Opened Half-Closed

RT(ms)

High frequency

5 5 9 . 6 2 ± 136.10 Low frequency

608.01 ± 1 7 0 . 8 3

RT(ms)

High frequency

535 .14± 114.36 Low frequency

609.98 ± 161.16

RT(ms)

High frequency

542.33 ±137 .69 Low frequency

639.42± 191.75

Accuracy (%)

High frequency

7 9 . 6 8 ± 13.84 Low frequency

6 5 . 7 8 ± 16.86

Accuracy (%)

High frequency

88 .77± 11.82 Low frequency

58 .82± 19.32

Accuracy (%)

High frequency 83 .96± 15.92

Low frequency 48.13 ±18 .11

Note: the numbers in the table refer to mean plus or minus standard deviation.

5.4 EXPERIMENT 3d

Experiment 3d aimed to examine whether Chinese characters with left-to-right form

were recognised faster or more accurately than those with top-to-down form. As

discussed before, vision is more accustomed to search from the left side to the right ride

than in other directions. In this experiment, I continued to adopt a lexical decision task,

as used in Experiment 3 a, to test the hypothesis that this visual habit is a superiority for

judging a character, namely the structure effect.

55

5.4.1 Method

Participants. Participants in the experiment were the same as those in Experiment 1.

Stimuli. On the basis of the structure property of a Chinese character, 40 horizontally

arranged (left-to-right structure) Chinese characters and 40 vertically arranged (top-to-

down structure) Chinese characters, matching in strokes, symmetry, closure, linearity

and connectivity in each frequency condition, and 60 pseudo characters were selected as

stimuli. Of the Chinese characters, half were high frequency characters and half were

low frequency characters across the two conditions. Horizontally arranged Chinese

characters were defined as those characters formed horizontally with their components,

e.g., "5tr" (lu4 - road) and "itr" (an4 - understand), and vertically arranged Chinese

characters as those characters formed vertically with their components, e.g.,

(shengl - sound) and "tP ' (zil - consult). All the selected Chinese characters were

listed in Appendix E. The pseudo characters were created according to the Chinese

character orthography (see Appendix G).

Design. It was a two-way within-subjects lexical decision task, in which reaction time

and response error were dependent variables and the structure and frequency of the

presented Chinese characters were independent variables.

Procedure. The whole procedure including the fixation, stimuli and mask presentation

time, size and location, and tasks, was the same as that in Experiment 3a except for the

56

stimuli and trials. Each participant was given 140 trials in total with 30 seconds rest

after every 70 trials. Fifty-five percent trials were used to judge real Chinese characters

and the remaining 45% to identify pseudo Chinese characters, but no participants were

told of this arrangement before and after the test.

The procedure was automatically monitored by STIM to record reaction times and

accurate responses for each participant. Before the task, each participant was given

clear instructions about the experiment (see Appendix H) and then ample practice trials.

Participants pressed the "1" button for a real Chinese character and the "4" button for a

pseudo character with thumbs. To balance the habituation of hands, half of the

participants responded with the left thumb for "1" and the right thumb for "4", and

others reversed the response pattern. Participants were tested individually in a dimly lit

room, and the whole experiment lasted approximately 6 minutes.

5.4.2 Results

Two participants' data were eliminated because of high response errors of horizontally

arranged characters (left-to-right) for low frequency (one reached 85% and another

95%). Reactions greater or less than 2.5 standard deviations were excluded from the

analysis and only correct responses were accepted.

The results were shown in Tablel7. Form and frequency of a Chinese character were

main variables in an analysis of variance (GLM-repeated measures). There was a

57

reliable structure effect for low frequency characters (RT: F(l,17)=5.53, MSE=2251.04,

p<0.05, and accuracy: F(l,17)=3.333, MS£=151.84, p=0.Q9) but there was no

significant effect for high frequency characters (RT: F(l,17)=3.34, MSE=l 121.26,

p= 0.09, and accuracy: F(l,17)=1.39, MSE=97.88, p>0.05). The finding that low

frequency Chinese characters with top-to-down structure are determined faster

contradicted the prediction.

Table 17 Mean reaction time and accuracy for identifying real Chinese characters or pseudo characters (n~18)

High frequency Low frequency

RT (ms)

Horizontally arranged 600.99 ±147.43

Vertically arranged 580.59± 133.58

RT (ms)

Horizontally arranged 716.38 ± 205.92

Vertically arranged 679.18± 182.88

Accuracy (%)

Horizontally arranged 80.56 ±16.26

V erti cally arranged 84.44 ±14.54

Accuracy (%)

Horizontally arranged 46.67 ± 19.48

Vertically arranged 54.17± 15.55

Note: the numbers in the table refer to mean plus or minus standard deviation.

Table 18 Mean reaction time and accuracy for frequency effect (n~18)

Horizontal arranged Vertically arranged

RT (ms)

High frequency 600.99 ±147.43

Low frequency 716.38 ± 205.92

RT (ms)

High frequency 580.59± 133.58

Low frequency 679.18± 182.88

Accuracy (%)

High frequency 80.56± 16.26

Low frequency 46.67 ± 19.48

Accuracy (%)

High frequency 84.44± 14.54

Low frequency 54.17± 15.55

Note: the numbers in the table refer to mean plus or minus standard deviation.

There was a significant frequency effect (Table 18) both in horizontally arranged

characters (RT: F(l,17)=29.90, MSF=4008.35, /K0.001; Accuracy: F(l,17)=52.24,

58

MSE= 197.88, /?<0.001), and vertically arranged characters (RT: F(l,17)=32.15,

MS!E=2721.14, p<0.001; Accuracy: F(l,17)=38.83, M££=212.46,p<0.001).

5.5 Discussion

The four experiments aimed to test a psycho-geometric framework for reading Chinese

characters. The important results of these experiments were that (a) almost all positive

psycho-geometric effects appeared in Chinese characters with low frequency except for

linear Chinese characters; (b) Chinese characters with top-to-down structure were

processed more easily than those with left-to-right structure which did not support the

general prediction of vision being from left-to-right; (c) no significant linearity effect

was found for the linear Chinese characters, and (d) there was a significant frequency

effect obtained in all the experiments.

The failure to observe psycho-geometric effects in Chinese characters with high

frequency might be caused by the following facts. Firstly, the frequency effect may

dilute the psycho-geometric effect in Chinese characters with high frequency. Secondly,

it is known that the processing of a character with high frequency is determined heavily

by its potential activity, automaticity, and level of processing. Seidenberg (1983)

pointed out that processing a word with high frequency is a top-down/holistic process

and processing a word with low frequency is most probably a bottom-up/analytic

process. The difference between the two processes would result in a difference in using

other visual cues including the above psycho-geometric cues. Thirdly, the process of

59

judging a Chinese character with high frequency is highly automatic and uses less effort.

Thus it is not difficult to conclude that other physical cues are less important for this

process. The story for characters with low frequency, however, is different. As it is

mainly a bottom-up process which is classified as a highly data-driven/perceptual

process (Roediger & McDermott, 1993), the processing takes advantage of any cues

available. A perceptual process highly depends on the perceptual cues of the stimuli.

Apparently, the role of those psycho-geometric cues manifest and thus a psycho-

geometric effect takes place. Finally, it is expected that if the perceptual environment is

changed, e.g., a faster presentation time, a strong mask, a distracted filler task and/or a

fast-search task other than lexical decision test, are adopted, it may produce a significant

effect or even reverse the effect.

It is well known that bilateral symmetry is often considered the most salient

organizational aspect of a stimulus in vision (see, e.g., Locher & Nodine, 1973; Mach,

1897; Palmer, 1989; Rock, 1983; Royer, 1981). Attneave (1957) and Day (1968) found

symmetrical shapes are judged less complex than asymmetrical shapes. That is,

symmetrical shapes, due to its redundant features, contain less information content than

do asymmetrical counterparts equated for complexity. Thomas (1963), and Noton and

Stark (1971) found subjects exhibited some preference for one side or the other a

symmetrical display, that is, subjects developed a one-sided visual scanning strategy for

symmetrical shapes. Locher and Nodine (1973) proposed that subjects use an early

organizing code that permits the generation of a feature code on the basis of partial

information. The advantage of symmetrical forms is due to the reduction in information

60

from redundant features. Royer (1981) further suggested the redundancy of features in

bilaterally symmetrical shapes makes the judging process faster.

In the present experiments, Chinese characters are just a kind of geometrical shape and

thus it should find a symmetry effect in which symmetrical Chinese characters are

processed more quickly when the perceptual condition is preferable.

Holes are a typical type of topological properties (See Casati and Varzi, 1995, and Chen,

1990 for the extensive and detailed descriptions). Chen and Zhou (1997) found subjects

perceived illusory hollow figures in which the conjoined holes underwent geometrical

transformations, indicating that the holes were detected as abstract topological entities

available at an early stage. Kao (2000) proposed that holes in Chinese characters could

facilitate processing. One of the experiments aimed to test this hypothesis which was

supported by the results showed that a completely closed Chinese character was decided

faster than a half-closed counterpart (closure effect).

Linearity (see Kao, 2000) was originally predicted as a positive cue forjudging Chinese

characters (linearity effect). The results were not supportive of this hypothesis. It

indicates that linearity is not a primitive and important feature for deciding Chinese

characters in a lexical decision task. The investigation in this Chapter showed a lower

popularity of both high and low linearity across the all Chinese characters although lines

appear in most Chinese characters. This investigation may imply a less importance of

linearity. In fact, to create a character using more linear lines would only increase the

61

strokes or complexity because when keeping the strokes constant, a character mainly

consisting of a single component would inevitably decrease the possibility of

combination. However, we should be cautious to draw this conclusion before other

tasks, stimuli, and presentation environment are tested.

There is no left-to-right structure effect but a reversed effect, i.e., a significant top-to-

down structure effect found. It is an interesting result although it contradicted the

prediction. The underlying causes are still not clear. One of the probable causes is that

the top-to-down structure (form) shows a clear appearance that permits the whole

character to be viewed at the same time, say, a holistic strategy, and although the left-to-

right form fits the visual habit, this construction leads to serial processing and is easy to

block a holistic/parallel processing which is believed to act more quickly.

It is also probable that Chinese was read top to down in the older texts or even in some

texts now. And this reading habit may have had a long-term impact in the later reading

of Chinese people. Chinese is written horizontally only after the invention of typing and

the Chinese mainland promoted a simplification movement in 1950's (Wang, 1973;

Zhou, 1998).

62

CHAPTER 6

TOPOLOGICAL AND SYMMETRICAL

PROCESSING OF CHINESE CHARACTERS:

AN EVENT RELATED POTENTIAL STUDY

6.1 INTRODUCTION

The above behavioural studies have proved that topological and psycho-geometric

properties facilitate Chinese character processing through a visual matching task,

priming task and lexical decision task. In the following experiments, the most salient

properties, topological properties and symmetry, were extracted to apply to an ERP

study.

Electroencephalography (EEG) is a technique in which the electrical activity of the brain

is measured and how this changes in association with stimuli, responses or mental states

such as attention is observed. EEG has very high temporal resolution which is in the

order of a few milliseconds although the spatial resolution is relatively low, i.e., it is

difficult to precisely locate where in the brain the signals are coming from. Usually the

electrical activity is recorded from electrodes attached to the scalp. ERP, a kind of

evoked potential, concerns the delineation of brain activity associated with specific

63

cognitive processes and the measurement precisely when and where this activity takes

place.

ERP components elicited by visual discrimination stimuli include the PI (the first

positive waveform among ERPs), N1 (the first negative waveform among ERPs), P2

(the second positive waveform), N2 (the second negative waveform), and P3 (the third

positive waveform) components. ERP components are labelled by the polarity (negative

or positive) and temporal order of appearance in the ERP. The peak latency ranges from

for the visual ERP components elicited during discrimination tasks are typically in the

following time ranges: PI (80-145 ms), N1 (100-200 ms), P2 (200-300 ms), N2 (200-

350 ms) and P3 (280-600 ms). (See O'Donnell, Swearer, Smith et al, 1997).

This chapter reports on 2 experiments that aimed to further test the effects obtained in

topological properties and symmetry in the behavioural experiments 1, 2, and 3a-d, and

tried to locate the cortex activation of the those effects and explore the time courses of

processing a topological property in a character pair and judging a character having a

symmetrical property.

6.2 EXPERIMENT 4

6.2.1 Method

Participants. Forty tertiary students (all male), aged 19-21, were evaluated. All

participants were right handed and had normal or corrected-to-normal vision at the

64

Fourth Military Medical University, with no history of neurological injury, psychoactive

drug or alcohol abuse and psychiatric diagnosis. Before the experiment, participants

were asked to clear their hair and to be free from any neural exhilarant for 3 hours and

none of these individuals had taken part in previous experiments. Informed consents

were obtained from all participants.

Design. This was a two-way within-subjects design, in which reaction time, response

error and ERPs (amplitude and latency) were dependent variables and topological

equivalence was the independent variables. In order to meet the standard design of ERP

experiments that required no fewer than 20 trials for each condition, the character

frequency factor was not considered in this experiment.

Stimuli and tasks. The stimuli and tasks were the same as in Experiment 1 (see

Appendix A). The same procedure as in Experiment 1 was adopted, except that the

inter-trial interval duration varied slightly from trial to trial in order to avoid a

habituation (average ISI 1.30 sec, ranging from 1.25 sec to 1.35 sec) and an EEG

recording was conducted simultaneously. Before the tasks, each participant was given

clear instructions about the experiment (see Appendix H) and then ample practice trials.

Participants were individually tested in a quiet, dimly lit and electrically shielded room.

EEG recordings. EEG activity was recorded continuously through 30 AgCl electrodes

attached to recording sites of the 32-channel Neuroscan system (see Appendix I for

electrode map across the scalp). Seven electrodes were placed at frontal (Fpl, Fp2, F7,

65

F3, Fz, F4, F8), six at left temporal (Ft7, Fc3, T7, C3, Tp7, Cp3), three at central (Fez,

Cz, Cpz), six at right temporal (Fc4, Ft8, C4, T8, Cp4, Tp8) and eight at parietal-

occipital (P7, P3, Pz, P4, P8, 01, 02, Oz). Behavioural responses were also recorded by

the Neuroscan system. Trials with artifacts larger than 0.5 mV were excluded from

further analysis. Horizontal and vertical EOG artifacts were corrected according to the

method developed by Elbert, Lutzenberger, Rockstroh, and Birbaumer (1985).

Impedances were maintained below 5 kilohm. The EEG was amplified and analog

filtered with 0.1 Hz to 40 Hz bandpass filters and a 60 HZ notch filter.

Data analysis. Some participants' data were eliminated due to excessive EEG artifacts

and response errors (errors over 60% in topologically different and equivalent, and self-

matching pairs). Since EEG recoding needed at least 20 trials for a condition, we did

not consider the character frequency factor in this experiment. Peak amplitude and

latency values were used to measure components in this study. Both peak amplitude

and latency values were obtained for each electrode site at the most positive or negative

voltage within the time window of interest using an automated algorithm. All amplitude

measurements were taken relative to average baseline voltage in the 100 ms interval

prior to stimulus onset. Only a clearly early positive component (P1') and a subsequent

negative component (N1'), both occurring earlier than PI and Nl) were measured at the

most positive voltage. The wavelength of PI' ranges from 40 to 80 milliseconds and

Nl ' from 80 to 160 milliseconds from all the pairs.

6.2.2 Results

66

6.2.2.1 Behavioural data

The behavioural results are shown in Table 19. Topological property (different or

equivalent) is main variable in an analysis of variance (GLM-repeated measures). There

were main effects of topological property for selected Chinese characters in both

reaction time (RT), F(l,37)=6.25, MS*£=683.81, p<0.05, and accuracy, F(l,37)=9.00,

MiSEK31.46,/K0.01.

Table 19 Mean reaction time and accuracy for identifying topological equivalent or different characters (n=38)

Different Equivalent RT (ms) 610.24± 147.55 625.24+161.53 Accuracy (%) 82.25+14.49 79.39+14.92

6.2.2.2 ERP data

Only significant EEG data are shown in Tables 20-21 (other EEG data are listed in

Appendix J1 and J2). The times course of occurrence of the P and N components (see

Appendix J1 and J2) indicated that the processes begin at the parietal-occipital areas,

through temporal areas to anterior frontal lobes, again to temporal lobes and finally goes

back to the parietal-occipital lobes. It can primarily suggest that the sites of TP8 in the

right temporal lobe and P3 in the parietal-occipital area (the visual cortex) were

demonstrated to associate with the topological processing. And F8 and Fp2 in the

frontal lobe, T7 in the left temporal lobe, Fc4 in the right temporal lobe, and Oz and P8

67

in the Parietal-Occipital Area were probably involved in processing topological

properties. So, the probable mechanism of processing topological properties is that the

visual cortex detects a pair of topological properties and then the information is sent to

temporal lobes foi furthei processing which is a type of language processing, under the

regulation of anterior frontal lobe.

The early ERP components (P: 40-80 ms; N: 80-160 ms) in processing topological

properties in Chinese characters showed that the process is pre-attentive.

Table 20 Mean latency and amplitude of the positive waveform (40-80 ms) across the scalp (n=37)

Electrode Latency Amplitude Spot Diff Ecju t p Diff Egu t p Anterior Frontal Lobe

F8 6 7 . 4 0 + 1 3 . 4 8 6 2 . 4 9 ± 15.20 1.75 0.09

Left Temporal Lobe

T7 60 .65+12 .61 64.81 + 12.94 1.85 0.07

Right Temporal Lobe

Fc4 5 5 . 0 8 + 1 1 . 7 7 60.22+14.51 1.94 0.06

Tp8 5 7 . 8 9 + 1 2 . 2 3 63.19 + 13.21 2.30 0.03

Parietal-Occipital Area

P3 1 .09+3.02 2 .06+3 .55 2.14 0.04

Oz 0 .17+1 .62 0 .54+1.91 1-76 0.09

Note: Diff-difference; Equ-equivalence, and one participant's EEG data was further excluded due to a bad waveform.

Table 21 Mean latency and amplitude of the negative waveform (80-160 ms) across the scalp (n=37)

Electrode Latency Amplitude Spot Diff Equ t p Diff Egu t p Anterior Frontal Lobe Fp2 9 5 . 8 9 + 1 6 . 3 0 101.78+19.34 1.84 0.07

Parietal Occipital Area

P8 -2 .73 + 2.88 -3 .17+2 .76 1-80 0.08

68

6.2.3 Discussion

The behavioural results are consistent with those in Experiment 1. The EEG results

only showed a positive wave (P component) and a negative wave (N component). Very

interestingly, the P (40-80 ms) and N (80-160) components showed here take place

earlier than PI (80-145 ms) and Nl (100-200 ms) reported by other studies (see

O'Donnell, Swearer, Smith et al, 1997). These two early components proved that

topological processing occurs at the very early stage. This result is consistent with

Chen's behavioural studies that a primitive and general function of the visual system is

the perception of global topological properties. It is known that the form of the early

components of EEG is almost certainly determined by the nature of the eliciting

stimulus (e.g., geometricity). Later components depend on the specific information

processing operations recruited by the stimuli (see Frith, 1997). In particular, the Nl, a

negative deflection occurring approximately 100 ms after the eliciting stimulus, is

generally regarded as an exogenous component of ERP modulated by stimulus

parameters and attention (Hillyard, Mangun, Wordorff, & Luck, 1995). As the visual

matching task used in the experiments involves less semantic processing, it is possible

that no further positive and negative components are produced.

Although ERP can not precisely map the activation of the processing due to a poor

spatial resolution in this condition, say, little is known about the relationship between

the signal recorded at the scalp and the activity in individual neurons or groups that give

69

rise to this signal, the results provide a clear flow-chart of the activation from the

origination to the end (probably some parts in the inferior temporal lobe and the superior

occipital area play an important role) and they also clearly show an early occurrence of

this process which is consistent with other behavioural studies in visual perception

(Chen 1982a, 1989,; Todd, Chen & Norman, 1998).

70

6.3 EXPERIMENTS

Since detecting symmetry is considered a primitive function of perception, it is expected

that the early ERP components, especially the exogenous components, the Nl and P2,

will play an important role, as those in processing topological properties. N2 has also

been suggested to reflect a central orienting response (Ford, Roth, & Kopell, 1976;

Squires, Squires, & Hillyard, 1975) and is thought to reflect a decision process related to

sensory discrimination of attended stimuli (Ritter, Simon, Vaughan, & Friedman, 1979).

A visual detection task with 80% standard and 20% target is intentionally used to

produce P3 component which has been related to several aspects of the processing of

task relevant stimuli (See review in Verleger, 1988). P3 is sensitive both to the

subjective frequency of a stimulus (Ritter, Vaughan, & Costa, 1968) and to the

relevance of a stimulus to the current task (Courchesne, Hillyard, & Galambos, 1975;

Donchin, 1979). The P3 has been proposed as an index of multiple cognitive processes,

including context updating, memory consolidation, orienting, processing termination

and decision making (Donchin & Coles, 1988; Johnson, 1988; Verleger, 1988).

Although enhancement of ERP late components (e.g., N2 and P3) to stimuli with an

unpredicted sudden change, temporal uncertainty (Sutton, Baren, Zubin, & John, 1965),

and to selective attention (Ford, Roth, Dirks, & Kopell, 1973; Hillyard, Hink, Schwent,

Picton, 1973) have been demonstrated, the role of these components in this experiment

should be cautiously interpreted. However, the P3 is not the initial ERP index of target

detection. Studies have tested earlier target detection effects in the Nl, N2, and

71

Selection Negativity at scalp sites over modality specific areas in the occipital, posterior

parietal and inferior temporal cortex (see review by Mangun, 1995; Naatanen, 1992).

The present experiment used 32 channel ERPs (both average reference and radial

current density representations) in a simple visual target detection (oddball) task adapted

from Courchesne, Hillyard, & Galambos (1975), in which infrequent targets

(symmetrical or asymmetrical Chinese characters) were interspersed into a stream of

frequent standards (symmetrical or asymmetrical Chinese characters).

6.3.1 Method

Participants. Participants in this experiment were the same as those in Experiment 4.

Design. This was a mixed design with repeated measures. The participants were tested

on both behavioural changes (i.e., reaction time and response accuracy) and ERPs.

Stimuli and procedure. The stimuli were 10 symmetric Chinese characters, e.g., HI (gu3

- hill) and (gaol - lamb) and 10 asymmetric Chinese characters, e.g., (zha4-

grasshopper) and % (lu3- bow), which were matched with frequency, structure and

topological properties (Appendix F). The stimuli size was of 0.780 high and of 0.72

wide of visual angle. Two of the stimuli were presented 20% of the time (target) and the

other characters were presented 80% of the time (standard).

72

At the beginning of the test, a fixation cross was shown at the centre of the screen.

Symmetrical and asymmetrical Chinese characters were tested separately. In the

symmetric condition, only symmetric Chinese characters were presented one by one in

white against a black background and in a random order across the total 250 trials at the

centre of the screen. In the asymmetric condition, except that the stimuli were

asymmetric Chinese characters, other designs were same as those in symmetric

condition. The participants were asked to respond to the target with the thumb of one

hand and to the standard with another thumb as quickly and as correctly as possible (see

Appendix H for detailed instructions). The intertribal interval duration varied slightly

from trial to trial in order to avoid a habituation (average ISI 1.30 sec, ranging from 1.25

sec to 1.35 sec). A practice session with the same stimuli but different sequence

preceded each condition before the test. Participants were given a 30-second rest after

the first 125 trials. After having finished the first condition (symmetric or asymmetric),

participants were given a 2-minute rest. In this period, experimenter tested the

Nuroscan system again and added some electrical gel to the caps if necessary. After the

practice session, participants began to participate in another condition.

To balance the habituation of hands, half of the participants responded with the left

thumb for target and the right thumb for standard, and others reversed the response

pattern. In addition, participants were also balanced in the sequence of tests. That is,

half of the participants were tested with symmetric-asymmetric order and another half

with the reversed order. Participants were tested individually in a dimly lit room. The

tests lasted approximately 15 minutes but the whole experiments including hair cleaning,

73

cap equipping, Neuroscan system reset and testing took about one hour for each

participant. The reaction times and error ratios were recorded for each participant.

EEG recordings

The EEG recording procedure and parameter were the same as in Experiment 4.

Data analysis

Three participants were excluded for further analysis due to excessive EEG artifacts and

response errors (over 20% for target and over 10% for standard).

6.3.2 Results

6.3.2.1 Behavioural Data

The behavioural results are shown in Table 22. Symmetry effects dissociated between

symmetric and asymmetric conditions. Only symmetrical targets were proven to be

judged faster than asymmetrical targets, but no difference was shown in standard stimuli.

Table 22 Mean reaction times (RTs) and response errors (ERRs) in symmetric and asymmetric conditions (n=37)

Symmetric Asymmetric t P Target

RT (ms) 492.70 ±50.68 511.76 + 58.42 2.57 0.02 ERR 0.1032 + 0.056 0.1027+0.062 0.043 0.97

Standard RT (ms) 398.16 ± 64.39 406.93 ±70.75 1.24 0.22 ERR 0.025 + 0.025 0.023 ±0.023 0.65 0.52

74

6.3.2.2 ERP data

Only significant EEG data were shown in Table 23-28 (other EEG data listed in

Appendix J3-J8).

For targets which usually need more effort, the time course of Nl, P2, N2 and P3 (see

Appendix J3, J4, J5 and J6) indicated that the processes begin at the temporal lobes,

then to the frontal lobes which may produce an attention, then to the occipital lobe,

again to the temporal lobe and the frontal lobes, then before returning to the parietal-

occipital lobes where a perceptual detection may occur, then again from the temporal

lobes to the frontal lobes where a decision making probably happens, then the temporal

lobe where semantic information may be activated, then to the central area for action

and ends at the parietal-occipital area, the visual cortex.

For standards that usually need less effort, the time course of Nl and P2 (see Appendix

J7 and J8) revealed that the processes start at the central areas, then immediately shift to

the frontal lobe which is presumably an attention process, then to the parietal-occipital

area and returns to the frontal lobes and to the central areas and end at the parietal-

occipital area, the visual cortex.

For the Nl component, the anterior frontal site, Fpl, is involved. It is supposed the

time course of Nl, probably associates with a pre-attention process, that is, the

orientation to the stimuli.

75

The P2 component heavily and extensively contributes to the symmetry effect although

other components also give their contribution. The anterior frontal sites, i.e., F7, F3, Fz,

and F4, left temporal sites, i.e., Ft7, Fc3 and C3, central sites, i.e., Fez and Cpz, right

temporal sites, i.e., Fc4 and Ft8, and parietal-occipital sites, i.e., P7, P3 and P8 are found

to involve in the process.

In the target condition, the significance tests for amplitude showed a shift of ERPs for

asymmetric condition, especially P2 to a negative direction. This significant shift

indicates that processing asymmetrical information is burdened more than processing

symmetrical information for targets. Although a higher spatial resolution test such as

fMRI is needed to specify the process, from the current results it is inferred that the

anterior frontal area and parietal-occipital area are believed to be crucial for symmetry

detection. In the standard condition, however, the significance tests for amplitude

showed a shift of ERPs for asymmetrical information especially P2 to a positive

direction. Accordingly, the shift indicates that processing asymmetrical information is

easier than processing symmetrical information, which failed to show this effect in a

behavioural test. It is interesting that a dissociation took place between the target and

standard conditions.

The N2 component in the anterior frontal site, F3, central area, Cpz, and the parietal-

occipital sites, i.e., P7, P8, 01, and 02 is reported to show significant differences in

processing symmetry.

76

As P3, the cential site, Cpz and the parietal-occipital site, P3 are highly associated with

the semantic process.

To summarise, given the primitive feature of symmetry processing and the function of

the cortex, the anterior frontal lobe and the parietal-occipital area are more likely to

involve the above processing. It may need a higher spatial resolution technology, such

as functional magnetic resonance imaging (fMRI) or positron emission tomography

(PET) to more precisely locate the activations for processing symmetry.

Table 23 Mean latency and amplitude ofNl for targets across the scalp (n=30) Electrode Amplitude Latency Spot Sym Asym T p Sym Asym t p Anterior Frontal Lobe Fpl 1 0 5 . 8 7 ± 15.61 1 1 1 . 2 0 + 1 5 . 6 2 2.01 0.05

Note: Sym-symmetry; Asym-asymmetry. Seven participants' EEG data were further excluded due to the bad waveform.

Table 24

Electrodc Spot Sym

Amplitude Asym T P Sym

Latency Asym / P

Anterior Frontal Lobe F7 8.92 + 2.44 8.06 + 2.73 2,59 0.02

F3 10.70 + 3.35 9.66 + 2.83 2.26 0.03

Fz 11.27 + 3.77 10.63 ± 3 . 4 4 1.96 0.06

F4 10.66 + 3.57 9.91 ± 3 . 0 7 2.48 0.02

Left Temporal Lobe Ft7 7.65 + 2.19 6.93 ± 2 . 5 8 2.45 0.02

Fc3 10.07 + 3.16 9.29 ± 2 . 8 3 3.21 0.01

C3 8 . 0 6 ± 2 . 7 5 7.59 ± 2 . 8 4 1.98 0.06 181.67+23.34 197.53+40.13 2.18 0.03

Centra! Area

Fez 10.91 ± 3 . 8 2 10.11 ± 3 . 2 2 2.85 0.01

Cpz 182.80 + 29.00 198.13 ±43 .46 2.56 0.02

Right Temporal Lobe Fc4 9.90 ± 3 . 3 1 9.18 ± 3.16 2.43 0.02

Ft8 7.75 ± 2 . 5 7 7.18 ± 2.39 1.85 0.07

Parietal-Occipital Area

P7 0.55 ± 1 . 7 9 1.55 ± 1 . 9 9 3.71 0.01

P3 3.66 ± 2 . 7 0 4.63 ± 3 . 8 0 1.75 0.09

P8 1 . 0 0 ± 2 . 6 2 2.09 ± 2 . 5 9 3.41 0.01

77

Electrode Spot Sym

Amplitude Asym t P Sym

Latency Asym t P

Anterior Frontal Lobe

F3 312.54 ± 21.91 325.00 ±29 .72 2.02 0.05

Central Area Cpz 0.29 + 3.87 -0.55 + 4.29 1.76 0.09 291.87 ±32 .19 274.93 ±42 .00 1.88 0.07

Parietal-Occipital Area

P7 266.13 ±39 .63 293.93 ± 3 9 . 5 2 2.72 0.01

P8 278.80±42.62 296.00 ± 5 0 . 2 4 1.98 0.06

0 1 264.13 ±34 .32 291.20 ±30 .51 3.73 0.01

0 2 266.00±49.58 292.20±48.22 2.50 0.02

Table 26 Mean latency and amplitude of P3 for targets across the scalp (n~30)

Electrode Spot Sym

Amplitude Asym / p Sym

Latency Asym t P

Central Area

Cpz 19.16 ±4.94 18.01 ±5.51 1.83 0.08

Parietal-Occipital Area

P3 470.13 ±32 ,73 457 .40± 35.33 1.98 0.0 6

Table 27 Mean latency and amplitude ofNl for standards across the scalp (n=37) Electrode Spot Sym

Amplitude Asym t p Sym

Latency Asym t P

Anterior Frontal Lobe F3 1 0 5 . 4 6 ± 12.49 110.11 ± 1 5 . 2 2 2 .55 0.02

F 4 105.84± 13.16 109.51 ± 1 4 . 5 0 1.85 0.07

Right Temporal Lobe Tp8 138.22 ± 39-93 123.08 ± 39.15 2.00 0 .05

Parietal-Occipital Area P7 -4.45 ±2.67 -4.85 ±2.59 3 .04 0.01

Sym Latency

Asym

312.54 ± 21.91 3 25.00 ± 29.72

1.76 0.09 291.87 ±32 .19 274.93+42.00

266.13 + 39.63

278.80+42.62

264.13 ±34 .32

266.00+49.58

293.93 + 39.52

296.00 + 50.24

291.20+30.51

292.20+48.22

Electrode Spot Sym

Amplitude Asym Sym

Latency Asym

Central Area

Cpz 19.16 ± 4 . 9 4

Parietal-Occipital Area

P3

18.01 ±5 .51 1.83 0.08

2.02 0.05

1.

470.13 ±32 ,73 457.40±35.33 1.98

0.07

2.72 0.01

1.98 0.06

3.73 0.01

2.50 0.02

Table 26 Mean latency and amplitude of P3 for targets across the scalp (n~30)

0.06

Table 27 Mean latency and amplitude ofNl for standards across the scalp (n=37) Electrode Spot Sym

Amplitude Asym Sym

Latency Asym

Anterior Frontal Lobe F3

F4

Right Temporal Lobe Tp8

Parietal-Occipital Area P7 -4.45 ±2.67 -4.85 ±2.59

105.46± 12.49

105.84± 13.16

3.04 0.01

110.11 ±15.22 2.55 0.02

109.51 ±14.50 1-85 0.07

138.22 ± 39.93 123.08±39.15 2.00 0.05

78

Table 28 Mean latency and amplitude of P2 for standards across the scalp (n=37)

Electrode Spot Sym

Amplitude Asym T P Sym

Latency Asym t P

Anterior Frontal Lobe

Fpl 8.03 ± 2 . 6 3 8.83 ± 2 . 9 6 3.31 0.01

F7 7.38 + 2.22 8.05 ± 2 . 2 9 3.54 0.01

F3 8.62 ± 2 . 5 4 9.68 ± 3 . 1 4 3.61 0.01

Fz 8.53 ± 2 . 7 8 9.64 + 3.09 4.82 0.01

F4 8.31 ± 2 . 5 5 9.3 7 ± 3 . 0 0 4.67 0.01

Left Temporal Lobe

Ft7 6.11 ± 2 . 0 8 6.72 ± 2 . 2 5 3.90 0.01

Fc3 7.67 + 2.44 8.74 ± 2 . 6 5 4.97 0.01

T7 4.34 ± 1 . 8 3 4.93 ± 2 . 0 3 3.48 0.01

C3 5.99 ± 2 . 2 2 6.98 ± 2 . 5 8 4.89 0.01

Tp7 1.94 ± 1 . 4 4 2 . 3 2 + 1 . 7 9 1.99 0.05

Cp3 4 . 6 3 + 1 . 8 1 5.13 + 2.12 2.97 0.01

Central Area

Fez 8.19 + 2.84 9 . 4 1 + 3 . 1 7 4.71 0.01

Cz 7.62 ± 2 . 6 8 8.88 ± 2 . 9 8 5.79 0.01

Cpz 6.88 ± 2 . 3 2 7.66 ± 2 . 6 3 3.34 0.01

Right Temporal Lobe

Fc4 7.64 ± 2 . 3 9 8.64 ± 2 . 8 0 4.64 0.01

C4 6,23 ± 2.39 7.21 ± 2 , 8 1 4.33 0.01 199.14+40.80 188.22 + 28.44 2.08 0.05

T8 4.46 ± 1 . 7 5 4.95 ± 2 . 0 5 2.39 0.02

Cp4 216.65 ±51 .39 206.65 ±43 .75 1.75 0.09

6.3.3 Discussion

There was an enhancement of the Nl in latency to asymmetrical stimuli indicating

identifying an asymmetrical Chinese character is more difficult than a symmetrical one.

Research has found that the primate visual system is bifurcated into two processing

pathways, a dorsal pathway projecting to the posterior parietal lobes that encodes spatial

location information and a ventral pathway projecting to inferior temporal cortex (IT)

that encodes the physical features of visual s u b j e c t s (Ungerleider & Haxby, 1994 ;

79

Ungerleider & Mishkin, 1982). The results here showed a fairly extensive activation in

temporal lobes, which is consistent with the above findings. The frontal cortex has been

regarded as a neural executive, which regulates and sequences related stimulus inputs,

motor outputs and target detection (Luria, 1973; Posner & Petersen ,1990; Pribram,

1973). Human hemodynamic neuroimaging studies have shown activation both in

frontal cortex and in modality specific areas of occipital, posterior parietal and inferior

temporal cortex in visual selective attention and target detection tasks (Corbetta, Miezin,

Dobmeyer, Shulman, & Petersen, 1990; Roland, 1985), which is consistent with the

results in this experiment. To detect a symmetrical feature, it is obvious that the

processing should also involve the frontal lobes (the executive centre of brain) and

parietal-occipital lobes (visual sensation and perception centre). The results are also

consistent with the prediction and previous studies using other tasks.

80

CHAPTER 7

GENERAL DISCUSSION AND SUMMARY

7.1 Psycho-geometric Theory of Chinese Character Reading

All the experiments conducted here are intended to investigate and examine a psycho-

geometric theory of Chinese character reading (Kao, 2000). This theory is based on

investigations on the evolution and construction of Chinese characters, and a series of

experiments on topological processing of visual perception and on Chinese character

writing.

7.1.1 Chinese Characters and the Characters Structuring

The reading of Chinese characters involves a process of visual spatial structuring of the

elements of characters. They are read within a subdivided square in which the execution

of strokes into characters, the shaping of the character, and the spacing and framing of

the character occur. The execution refers to the basic formation of strokes within a given

character and their structural interrelationships. The shaping is a process of organising

the various strokes to conform to the style of the character, and the spacing and framing

is the layout and spacing of characters, as well as their position in columns and rows

(Billeter, 1990).

81

The purpose of shaping a character is to ensure its coherence and autonomy relative to

other characters in a given reading context. The formation of a character involves

inscribing it in a square and then centring it for each character, it is important that its

centre coincides with the midpoint of the square and its strokes be aligned according to

the visual-spatial patterns of the previously established character. This is a visual effect

quite different from that of English letter formation.

Central to the perceptual organisation of the character from within the reader's cognitive

experience is some properties underlying the visual-spatial structure of Chinese

characters. On a more visual spatial level, several topological principles of visual

perception are pertinent to the cognitive map of the character produced in the act of

reading. These include the presentation of global and detailed views of the objects,

connectivity, inside-outside relationships, closure, co-linearity, size, orientation and

symmetry. In the process of reading, the reader's perceptual shaping of the character is

influenced by the patterns within the character which cause his/her perceptual and

cognitive conditions to engage in corresponding adjustments and representations. This

dynamic process would result in his perceptual, cognitive and physiological responses to

vary in respect of the visual-spatial configurations of the character (Kao, 2000).

Examples of Chinese characters containing different composition of the visual

geometric properties are provided, for the purpose of illustration, in a more stylised print

form.

82

Symmetric characters Parallel characters Connected Characters

H BB M °r

Jll § I I ttl X ft • R

l$l S ^

Non-svmmetric characters Non-parallel characters Non-connected characters

M M % a r &

!$b / §

sh A n <b

i t Jll A R

Closed characters Linear characters

ffl • B o° 1 S ES Da

I B B t t

Unclosed characters Non-linear characters

% Jo ~EL

* £ & A

St A 3 &

Parallel characters Connected Characters

H ffl M °T

Jll S !pi L±J l$l % § ^

Non-parallel characters Non-connected characters

M MS % a r &

M !& /S

/ h A n ' h 1 L j l l A H

Closed characters Linear characters

E 0 O B g d D

M @ ES Ob

3E B HI D±

Unclosed characters Non-linear characters

± -EL 3 %

7X2 Principles of Chinese Character Writing

A conceptual framework has been advanced to highlight the act of Chinese character

reading. The following is a summery of some of the key points (Kao, 2000).

83

A square is a peifect geometric pattern as it incorporates hole, linearity symmetry,

parallelism, connectivity, and orientation all in one figure. A Chinese character is seen

to portray an imagery or visible square. With an implied correspondence between the

shapes of the square and the character, the characters may vary in terms of the extent to

which they possess the geometric properties of the square as well as other non-

accidental properties. Research has shown these advantages in human cognition and

bodily activities in Chinese calligraphic writing, e.g., psychophysiological changes,

taking place during calligraphic writing that varying with the geometric variations of the

characters, include heart-rate, respiration, blood pressure, finger pulse volume, EMG,

EEG and skin temperature (Kao, Lam, Robinson & Yen, 1989). Particularly, Kao &

Goan (1995) found that cognitive changes associated with the geometric variations of

the characters include clerical speed and accuracy, spatial ability, abstract reasoning,

digit span, short-term memory, picture memory, and reaction time.

Stylistic variations of Chinese characters reflect individualised forms of the strokes

organisation in the character. In the recent years, Kao (2000) has conducted a series of

studies to tackle the issues on the cognitive correlates of the visual geometric properties

of Chinese characters. These are reviewed from the perspective of visual recognition

associated with Chinese reading and handwriting. The underlying hypothesis is that

variations of the visual-spatial properties of the characters would result in corresponding

cognitive changes in the process of Chinese reading.

7.1.3 Effects of Character Geometricity on Visual Recognition

84

A square is the simplest visual pattern (Koffka, 1935). It incorporates, as in the case of a

Chinese character, not only patterns such as co-linearity, closure, symmetry, continuity

and balance, but also other properties of connectivity and parallelism. Characters may

vary in terms of the extent to which they possess the geometric properties of the square

in addition to its geometric configuration in character structure. Kao recently (2000)

analysed the most primitive writing systems including the Egyptian writing, the

Sumerian script and the Chinese oracle script. He found the existence of common visual

properties in primitive writing systems: tendencies of being pictographic closed

symmetric and parallel. These features of the primitive writing systems are direct and

natural projection of our perception of the outside world. Chinese script of the present

day remains the only written language that inherits most of the distinctive visual

characteristics of its ancestors.

To test whether the visual properties adhered to the characters could affect the

orthographic processing of Chinese character, we conducted two experiments (Chen &

Kao, 2002). The first experiment hypothesised that the visual-spatial properties inherent

in the characters are quickly utilised to facilitate the orthographic processing of the

characters. The visual-spatial properties considered were linearity, parallelism, closure

and symmetry (see Table 29 for examples). In a within- subject design with two levels

of character complexity (fewer than 9 strokes versus more than 10 strokes) and three

levels of visual-spatial properties of pairs of character stimuli (rich-rich, rich-poor, and

poor-poor), fifty grade 4 children participated in a visual judgement task measured by

85

reaction times and errors. The results suggested that the visual-spatial properties are

utilised quickly enough to provide a perceptual basis for Chinese character processing.

Furthermore, the visual judgements were more quickly produced and had fewer errors

for pair characters with rich (rich-rich) visual properties than those with poor (poor-poor)

visual properties. These findings were consistent with the hypothesis on the facilitating

effect of non-accidental properties on orthographic processing of Chinese characters.

The richness of the geometric properties inherent in the Chinese characters affects our

perceptual and cognitive processing directly (Chen & Kao, 2002).

Table 29

Richness of the geometric properties in Chinese characters

Visual Property Character Sample

p^ l H O O i

P+L+C M, n±, I'J, I I

P+L+c+s ffi.JK.P,*

Notes: P = Parallel, L = Linear, C = Closure, S = Symmetric

In a second experiment (Kao & Chen, 2000), Chinese characters presented in the square

and rectangular shapes were compared in a visual recognition task. Measured by

response time to the onset of the stimulus character on a computer screen, the characters

presented in the squared style were responded to more quickly than those presented in

the rectangular style. A second study examined the effect of angularity of stroke linkage

in Chinese characters as well as in English letters on a recognition task (Kao & Chen,

86

2000). Using college students and measured by multiple recognition tests, the subjects

performed significantly better in characters and letters with smaller angles than with

larger angles. A recently completed experiment compared the functional localization in

the cortex in reading Chinese characters as well as Chinese Pinyin (Kao, Chen, Li,

Mathews, Fu & Gao, 2000). The latter is a phonetic system based on the spelling of

Chinese sounds by a visual script comprising largely English alphabetic letters.

Using the functional magnetic resonance imaging (fMRI) technique, Kao et al. (2000)

found that reading Mandarin characters involves more and different cortical sites for

processing than Pinyin reading of the same Chinese sounds, although at the same time,

both types of reading share certain common sites. A difference in cortical activation has

therefore been observed between the two scripts, which vary in terms of the visual-

spatial form and complexity. This initial finding is line with our theoretical expectation

on differential neurocognitive processing of different scripts as a function of the

differentiation and richness of their respective visual spatial properties therein. It has

implications toward our understanding of the visual spatial activating effects of the CCH,

because this graphic act involves visual and neurocognitive processes, but also motoric

action.

These three experiments have provided some empirical evidence to the validity of our

stated hypothesis, that is, characters having some geometric properties, such as

connectivity, linearity, hole(s) and symmetry are processed quickly. This study, through

a visual match task and a lexical decision task, has shown the geometric property effects.

87

7.2 Topological Perception and Functional Hierarchy in Form

Perception

According to a feature integration theory (Treisman, 1988), visual identification should

include two processes, i.e., feature detection and integration. Feature detection such as

colour and size occurs earlier than integration. Treisman (1988) does not include a

topological processing in the early stage, that is, her theory holds that a global

processing, if it really exists, should take place later than a feature detection process.

Chen (1989) argued against this theory and proposed a more primitive topological

process appearing earlier than a feature detection process.

Chen (2001, p. 288) argued that, in addressing the most fundamental question of

'Where visual processing begins', the theories of perception can be segregated into two

contrasting lines of consideration: 'early feature-analysis' (that is, from local to global

processing) and 'early holistic registration' (that is, from global to local processing).

Early feature-analysis view holds that objects are initially decomposed into separable

properties and components, and only in subsequent processes are objects recognised, on

the basis of extracted features. The early holistic registration approach supports a 'from

global to local' view that Wholes are organized prior to perceptual analysis of their

separable properties or parts, as indicated by the conception of perceptual organization

in Gestalt psychology.

The problem of feature binding is then essentially a consequence of the particular local-

to-global assumption. However, from the global-to-local perspective, the problem of

feature binding may be a wrong question to ask to begin with, while the Gestalt concept

of perceptual organization serves to reverse this inverted position. Inspired by the

analysis oi invariants over transformations, particularly shape-changing transformations,

Chen (2001; Todd, Chen & Norman, 1998) developed a topological approach to

describe precisely the nature and rules of perceptual organization, with respect to

Klein's Erlangen Program. Klein's Program provides a formal way to define a kind of

geometric properties as a kind of invariants preserved under a specific transformation

group, and stratify branches of geometry with reference to their relative stabilities under

this transformation group. The more general is a transformation group, the more

fundamental and stable are the geometric properties preserved under this transformation

group. Particularly, topological properties, such as connectivity and holes, are most

fundamental and stable, because the topological transformation group ('one to one and

continuous') is the most general one.

Alternative geometries can be devised for which constraints on corresponding

transformation groups are varied. Along the Program, a hierarchy of geometries were

built up in an ascending order of relative stability: Euclidean geometry, affined

geometry, projective geometry, and finally topology with the highest stability. A fairly

large set of behavioural data revealed that topological perception plays a fundamental

role in perceptual organizations, such as distinguishing figure from background, parsing

visual scenes into potential objects, and performing other global, Gestalt-like operations.

89

Particularly Chen and his colleagues (Chen, 2001; Todd, Chen & Norman, 1998) found

that the relatives salience of different geometric properties is remarkably consistent with

the hierarchy of geometries stratified by Klein's Program. Since only from the

perspective of the invariants over the topological transformation can the precise

meaning of topological properties be grasped, and since at the core of Klein's Program

lies the idea of transformations and invariants preserved under transformations, this

framework claims that visual perception may work by abstracting invariants of forms

under changes, and the primitives of visual representation should be considered

invariants at different levels of geometry, including particularly topological invariants

(as opposed to concrete and simple components of objects, such as line-segments

commonly accepted). Form such perspective of invariance perception of this framework,

the relationship between different geometrical properties, particularly between global

topological perception and perception of local geometrical features, can be clarifies as a

functional hierarchy of form perception. That is, global topological organization is prior

to the perception of local features, and the time dependence of perceiving form

properties is systematically related to their structural stability under change, in a manner

similar to the Klein's hierarchy of geometries: in a descending order of stability or from

global to local, topological properties (typically the number of holes), projective

properties (typically co-linearity), affined properties (typically parallelism), and

Euclidean properties (typically orientation ,location, and mirror-symmetry). Chen

argued that these results demonstrate strong evidence for those invariants at different

levels of geometries have psychological reality as the primitives of visual representation.

Chen's theory is consistent with the observations on the development of mathematics in

90

children by Piaget (1953), in which Piaget found children first developed the concept of

topological geometry and then other geometries, which is reversed to the development

of geometry (from Euclidean geometry in ancient Greece to topology in the late

nineteenth century).

Evidence supporting topological perception is illustrated in topics of visual sensitivity

(Chen, 1982a, 1990), apparent motion (Chen, 1985; Zhuo, Zhou, Rao, Wang, Meng,

Chen, Zhou, & Chen, 2003), illusory conjunctions (Chen & Zhou, 1997), and the

relative salience of different geometric invariants (Han, Humphreys & Chen, 1999a,

1999b; Pomerantz, Sager, Stoever, 1977; Todd, Chen & Norman, 1998).

The visual matching task only produced a topology effect in Chinese characters with

high frequency but not in low frequency characters. On the Contrary, the direct priming

task induced an effect in Chinese characters with low frequency but not in those for high

frequency counterparts. As pointed out earlier, a Chinese character with high frequency

is usually processed through a top-down process. These characters can access to the

lexicon with less effort, say, automatically. It is not necessary to take advantage of other

redundant information to process a character with high frequency according to an

economical principle, which has important biological significance (see Kahneman,

1973). The author believed the higher complexity of the Chinese characters with low

frequency prevented a topology effect from occurring in a visual matching task and a

conceptual driven process, rather than a perceptual or data driven process, in the high

frequency condition failed to activate a priming effect (See Moscovitch, 1992). It is

91

expected that if the presentation environment changes, such as using more rapidly

stimuli or reducing discrimination resolution rate of targets, the effects may manifest. In

addition, I claimed that the low visibility has damaged the identification of characters

with low frequency. It should be cautious to draw this conclusion particularly before an

experiment, that has matched the visibility between the characters with high and low

frequencies (i.e., relatively reduce the complexity of characters with low frequency), has

carried out.

Although this study could not prove which happened earlier, the results have clearly

shown an involvement of topological processing in identifying Chinese characters in a

tachistoscopical environment. That is, topological organization of the characters affects

Chinese character identification. The results are also supported by the subsequent ERP

study. The conclusion reminds us that a topological involvement should be considered

when we are designing an experiment in Chinese language reading and writing. In

particular when a morphological priming paradigm (i.e., a prime which is

morphologically similar to a target will reduce the reaction time for the target) is

adopted, we should treat topology as a control variable. The findings in Experiment 2

showed that a character (prime) which is topologically equivalent of the following

character (target) can facilitate the response to the target, revealing a topological

priming effect. That is, there may be a confounding of variables in a morphological

priming task because topology also contributes to the priming effect. In fact, no

previous studies in Chinese language cognitive research have distinguished this

92

difference. So, it is recommended to conduct a meta-analysis for all the studies using a

morphological priming paradigm.

7.3 The Neural Mechanism of Geometric Property Processing:

Evidence in Topology and Symmetry

A follow-up event-related potential (ERP) study revealed that topological processing

produces an early positive component and then an early negative component, with both

occurring earlier than the reported PI and Nl respectively. The results indicated that

topological processing takes place at a very early stage and probably is pre-attentive

which supports the hypothesis by Chen (1982a, 1989) and found some brain areas

including some locations in the temporal lobe, the anterior frontal lobe and the occipital

lobe, associated with the process, which are consistent with the previous studies by Han,

Fan, Chen, and Zhuo (1997). The working loop of the activation should be analysed

further, especially in contrast to an fMRI or positron emission tomography (PET) study

to more precisely locate the activation areas.

ERP measurements showed a dissociation processing symmetrical and asymmetrical

information between target and standard conditions. And an extensive involvement of

P2 may indicate the processing is strongly driven by an exogenous component and rely

on the processing of physical features of the Chinese characters, such as symmetry in

this study. The fact that only an Nl and P2 occur in processing symmetrical and

93

asymmetrical information in the standard condition indicated that the process should

finish at the time course of P2, that is, less than 236 ms (the longest latency in P2).

7.4 Present and Future

7.4.1 Implications

Much research in Chinese character processing in the past three decades has been

focussed on the role played by phonological processing in character processing (See also

Kao, Leong and Gao, 2002). This study took another perspective, i.e., a pattern

recognition perspective, to investigate how geometric properties in a Chinese character

affect the recognition and identification. The present study provides evidence for the

psycho-geometric theory of Chinese character reading, which is a unique and

completely new exploration for Chinese reading. This exploration has impacts on the

construction of linguistic processing and enriches the theory of Chinese language study.

Furthermore, the study erected a link between Chinese character processing and pattern

recognition. It is important to study the unique features of a character, that is, the

geometric properties.

In practice, the findings are helpful for Chinese character learning. It is expected that

children and foreigners who are learning Chinese characters may start from the

characters having some geometric properties such as hole, connectivity, symmetry and

straight lines.

94

7.4.2 Limitation

The conceptual development of the topological properties for character processing needs

further clarification, because Chen's work deal with pure visual forms without the

semantic context, while the present study tackles content-rich Chinese characters.

Similarly, the psycho-geometric properties should be more clearly defined, characterised

and distinguished from the mathematically defined topological properties.

It is regrettable that only male subjects were used in this study. Since there were fewer

female students in the military, we could only get enough male participants to

participate in the experiments. Although no research has shown a sex difference in

geometrical processing, it would be preferable to involve enough female subjects in

future.

7.4.3 Present and Future Directions

The present study examined the geometric processing of Chinese characters, which is

interpreted by a psycho-geometric theory through a behavioural and ERP approach.

During the last decades, research on Chinese character processing has been heavily

focused on phonology and semantic processing. This study explored a new direction to

investigate how geometric properties are crucial recognise a character. It is important to

point out that sort of studies are necessary to clarify the cognitive and neural mechanism

95

of Chinese character reading. I have tried ERP in this study, it is reasonable to think of

other neuroimaging approaches, such as fMRI, PET and magneto-encephalography

(MEG) in the geometric processing of Chinese characters. In fact, some fMRI studies in

phonological processing of Chinese characters have been published (e.g., Chee, Tan, &

Thiel, 1999 Me, Tan, Tang et al, 2003; Tan, Spinks, Gao et al., 2000).

Applying the psycho-geometric theory to Chinese character writing is also an important

move, particularly in learning how to write Chinese characters for children and

foreigners. In the past two years, I have closely observed my son, Tian Tian who is now

in his three years old, to learn to write Chinese characters. Interestingly, almost all the

first characters he has learned are those having straight lines, holes, symmetry, and so on.

The examples of his first learned characters include '41 ' (centre), 'J3' (moon), ' 0 '

(sun), 'I'u'i' (high). After almost 6 months, he gradually can write other characters, like

VX' (water).

7.5 Summary

Over 60% of Chinese characters are of the left-to-right form, around 20% of the top-to-

down form and the remaining of fewer than 20% of other structures. The frequency of

characters is inversely proportional to the number of strokes, i.e., the more frequently

the characters are used, the fewer strokes they will have. Specifically, for low frequency

characters, almost no correlation exists between frequency and stroke number. For high

96

frequency characters, they will have about two strokes fewer than those with mid-

frequency or around three strokes fewer than those with low frequency.

Most of the frequently used Chinese characters (65% in total) consist of hole(s) with

most of their containing 1 or 2 holes. No apparent difference is revealed in the

distribution of hole(s) across frequency (959 characters for high frequency, 1,069 for

mid-frequency and 945 for low frequency).

Only 6% of the characters are connected in construction but the distribution of this

property (characters with connectivity) is extremely skewed. Among the first 300

characters around 30% of them are connected and 71 percent of the connected

characters are of high frequency, suggesting that the most frequently used Chinese

characters are connected.

There are 260 characters with high linearity and 212 with low linearity but this finding

may not apply to the traditional Chinese characters. Thirty-nine percent of the

characters are fully or partially symmetric and most of the fully symmetric characters

are of high frequency. Partially symmetric or asymmetric characters are approximately

equally distributed across the frequency of usage. There exist some characters with two

or more symmetries. Moreover, there are 86 characters in total with weak balance, that

is, 9 with high frequency, 31 with mid-frequency and 46 with low frequency.

97

Neither frequency effect was found in both topologically equivalent and different

chaiactets, nor did the effect occur in either a visual matching task or a lexical decision

task (priming paradigm). As discussed by Ferstl & d'Arcais (1999), a frequency effect

is more likely to happen in a semantic process. Unfortunately, the process involved in a

visual matching task and a priming lexical decision task, both of which are heavily data-

driven, unintentionally diluted the semantic involvements or conceptual-driven

processing. Thus, it was reasonable to conclude it should not manifest a frequency effect,

although we should be also cautious in our interpretation before any further studies are

conducted.

No linearity effect was found for both Chinese characters with high frequency and those

with low frequency. The causes of these results are still unclear. If the results can be

further confirmed by other studies, it may be important to claim that linearity is not a

positive factor of Chinese character reading. If so, the psycho-geometric framework of

Chinese reading and writing by Kao (2000) may be revised to adapt this conclusion.

In a series of four experiments through a classic lexical decision paradigm, we found a

symmetry, a closure, and a structure (radical arrangement) effect in Chinese characters

with low frequency but not for high frequency, except for the linearity effect. The

causes of this phenomenon is those Chinese characters with high frequency induced

automatic processing requiring less effort which make the other perceptual cues, such as

symmetry, closure and construction, less useful (See Forster, 1994, for a search model

and McClelland & Rumelhart, 1981, for a connectionist model to account for frequency

98

effects). The results proved that symmetry, closure and a top-to-down form are a

positive factor in Chinese character reading, which coincide with the psycho-geometric

investigation of the commonly used Chinese characters in Chapter 3 of this study. The

results also implied that we should think of these factors which may affect Chinese

learning when we conduct research using Chinese characters as stimuli or when we

develop other research work with Chinese such as a simplification movement on

Chinese characters.

An event-related potential (ERP) study has shown that topological processing produces

an early positive component and then an early negative component, with both occurring

earlier than the reported PI and Nl respectively. The results indicated that topological

processing takes place at a very early stage and probably is pre-attentive and discovered

some brain areas including some locations in the temporal lobe, the anterior frontal lobe

and the occipital lobe, associated with the process.

ERP measurements showed a dissociation processing symmetrical and asymmetrical

information between target and standard conditions. And an extensive involvement of

P2 may indicate the processing is strongly driven by an exogenous component and rely

on the processing of physical features of the Chinese characters, such as symmetry in

this study. The fact that only an Nl and P2 occur in processing symmetrical and

asymmetrical information in the standard condition indicated that the process should

finish at the time course of P2, that is, less than 236 ms (the longest latency in P2).

99

Notes:

1 The Chinese language also has an alphabet invented in the late Qing Dynasty, which was created to describe the pronunciation of mandarin or Putonghua. With the view of annotating Chinese characters in the Western alphabet, a new romanisation called Pinyin was adopted in the Chinese mainland since 1950's, which can better describe Chinese pronunciation than the Wade-Giles system, except that one has to grasp it with a slight change in pronouncing some of the consonants from the view of English language. The number followed by the Pin-Yin indicates the tone of this character. There are four intonations or tones in Putonghua namely: ' 1' represents Ying Ping, a low flat tone, e.g., A (bal-eight), '2' Yang Ping, a high flat tone, e.g., fflt (ba2-pull), '3' Shang Sheng, an ascending tone, e.g., IE (ba3-target), and '4' Qu Sheng, a descending tone, e.g., @ (ba4-father). (see Ann, 1987)

2 High frequency refers to more than 50 occurrences and low frequency to less than 5 occurrences out of 1 million occurrences, and the remaining are in mid-frequency.

3 A pseudo-Chinese character is made according to the orthographic principles of a real Chinese character but it is never a real Chinese character.

100

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116

Group Group

1 + X • 1 i f

2 a t 2 fK

3 f f Pf 3 np 5®

4 A r 4 m &

5 R Jf 5 i e IS ft

6 n a i 6 i & £

7 i t - b A 7 b ih

8 § iftL f5n 8 / L

9 lLj — 9 J 6

10 t} * 10 s 351 n

11 % £ in 11 ft &

12 A A A 12 ft m fa

13 % % ffl 13 n£ #n @

14 % M s 14 m IP® n

15 # R 0 15 t i 0

APPENDIX A

Low Frequency

Group

• i % if

% 2 m ® m

U 3 op $£ «

$ . 4 & £f

f x 5 ?E IS ft

7 i t - b A 7 b ^ ih

8 g l&L 8 *5 ^ /L

9 i l j ^ - 9 3 9 # * S

10 ^ j j & io 4- M ^

11 ^ £ in ii ft fl* &

12 A A A 12

13 3£ ^ ffl 13 R& @

14 S S S 14 90 ^ 0

15 & K 0 15 ^ ^

Note: Group 1-6 are distinguished by holes, Group 7-12 by separation/connectivity and Group 13-15

by inside-outside distinction

117

Symmetric Asymmetric Symmetric : Asymmetric * 7 ¥ % * a dhfcr /jyjN & t 4 * m 111 % s>& 5 M $3 m Stfc l''J £ ¥ n )k A ZK 31

j] £ M M s

hi IE -A. a # • & 3J

S& # # n 1-5 itt A E B

II it $>L

m & i f £

m r ft

¥ ft

APPENDIX C

Stimuli from Experiment 3b

Hieh Frequency Low Frequency

Linear P * r —•

Non-linear Linear Non-linear

± 111;

tfi$ m ± 111; £ TSC

10 lR 6

.It M

IE & m

# Iii

m # FP #

Iii w* E FP lin Pi m UK M M #f-la. # m & £

f - 5§

APPENDIX B

Low Frequency

:lt m #

x & r m

Symmetric

dhfcr m

&

& B

Jft m #

g

Asymmetric

% & JEE s w m & M

m m

•x ft

APPENDIX C

Stimuli from Experiment 3b

High Frequency Low Frequency

Linear ± lit 10 .It IE # 11

Non-linear

z & M 2

Linear

n si

«£

Non-linear

0E

w m m &

118

APPENDIX D

Stimuli from Experiment 3c

High Frequency Low Frequency Closed Opened Half-closed Closed Opened Half-closed

h -'j* is) m ¥ n |P| ft; |Hlj @ -g $ m !•- @ m m m m m m & is |l*| 1̂3 0 Sii H m & w i ft ia m I. ft ® fr s E! lis fc3 0 % fS [5| i ft Ii ® $ W 0 ^ H S IS ff n it ra iii s fi

119

APPENDIX E

Stimuli from Experiment 3d

High Frequency Low Frequency Right-to-left

ifii

M m m m # &

ast ffi

Sk m m Mi

Mi hi

m

Top-to-down

&

M K

& S8

m w

Right-to-left

© iK m,

I®

if ffi

Top-to-down

bb

faf* £

120

APPENDIX F

Stimuli from Experiment 5

Target

Standard

Symmetric Asymmetric

ife.

ii m

TSf.

121

m

APPENDIX G

Pseudo Chinese Characters Used in the Experiments

CODE 0 1 A B C D E F AAA

AAB

AAC

AAD

AAE

AAF

ABA

ABB

ABC

ABD

ABE

ABF

ACA

ACB

ACC

FF j f i

M

m m

ft

* ^

* • m ®Xi /sue

i t ££

«

cr * t=T s" M- rfj

•fe S IE

9k fi t H

BjE ft

•» a IE

fi S I

e n

3? & & s§ m IS & t& # Btfe 31 i i ©c tH W 4S Sft # K

$ S S 41 ijS H PI

A*r

t

ft

- t t

tfr

JE

-±r TO •& &C

M?P •C/»

jfc -&T z*z

& i a

m m m

m «•

m « @ i t

* jK

fcX I S

# J$

M fis *t!» /Jr3

# jGE i * #

W ft SL iff 14 ft « ®

« m ® m

& a # j® ®

BS

hi

fit*!

-**-

't> TX ^ M

* JB3 3fc « l

IS tt ffi EC If Sfc « ff II

Jig £ Ifc

m # as El # 5

^ M J$ BB ^ gfe-

^ ^ ^ ® £? £?

$ t « ? i t ffi

££ X!l I'J ill

Vll T»»*\

$ % 1 «

f t m « # f

^ i t

122

APPENDIX H

Instructions in Experiment 1

This is an experiment on visual perception. A fixation figure with 'fence' form

will be first presented at the centre of the screen for about 1 second. After the

fixation figure disappears, two Chinese characters will be simultaneously presented at

the left and ride sides of the figure respectively. After the presentation, a mask

consisting of random dots will cover the Chinese characters immediately. You are

asked to determine whether the two Chinese characters are exactly the same character.

If identical, please use your left/right thumb to press the button '1' and if not, please

use your another thumb to press '4' button on the 4-key board. You are also required

to respond to what the first comes to your mind as quickly and as correctly as possible.

If you cannot clearly identify the characters, you can give a decision based on your

own judgement but be sure you do not miss any response. And now you will be given

a series of practice trials. (Translation from Chinese)

123

3ic ̂ ^ . 1 ^ Hi it—

^ ± ^ s i n i o tmmm, im« 1 " m>, *nn*iw!, im « 4 "

^ ^ H 7 M ^ ^ i ^ p ] - f g . l E l i i t k f f l m - - ^ f : # i ± l ^ S J S o # ^ M ^ t M $ P J , H i t

124

Instructions in Experiment 2

This is a lexical decision test. A fixation figure with 'fence' form will be first

presented at the centre of the screen for about 1 second. After the fixation figure

disappears, two characters will be presented one followed another without break at the

same place of fixation figure. After the presentation, a mask consisting of random

dots will cover the Chinese characters immediately. You are asked to determine

whether the second presented character is a real Chinese character or not. If it is,

please use your left/right thumb to press the button ' 1' and if not, please use your

another thumb to press '4' button on the 4-key board. You are also required to

respond to what the first comes to your mind as quickly and as correctly as possible.

If you cannot clearly identify the characters, you can give a decision based on your

own judgement but be sure you do not miss any response. And now you will be given

a series of practice trials to understand what are called real Chinese characters and

pseudo-characters. (Translation from Chinese)

125

f4.'jN'f ;] :^^jn» i t |W|—'fiS^#—Itl— RtJs

$ & • — t Iii fft 51 o ® Iff % - Hk iti W&

, i ; ^^ f i<J^ , £fl "2j"> ifn " A " ¥•, M ^ * ^ o *

" 1 " f t . " 4 " i .

m&im

mm -*m>u

126

Instructions in Experiment 3a-d

This is a lexical decision test. A fixation figure with 'fence' form will be first

presented at the centre of the screen for about 1 second. After the fixation figure

disappears, one character will be presented at the same place of fixation figure. After

the presentation, a mask consisting of random dots will cover the Chinese characters

immediately. You are asked to determine whether the presented character is a real

Chinese character or not. If it is, please use your left/right thumb to press the button

'1' and if not, please use your another thumb to press '4' button on the 4-key board.

You are also required to respond to what the first comes to your mind as quickly and

as correctly as possible. If you cannot clearly identify the characters, you can give a

decision based on your own judgement but be sure you do not miss any response. And

now you will be given a series of practice trials to understand what are called real

Chinese characters and pseudo-characters. (Translation from Chinese)

127

(1-4)

i i M - t f i A . u . j , [ ^ j n ^ f # o r *

{ju^hivfo :m i # j g i i ^ n m ^ ,

- 1 bi 11 -ii in & t m m is b si o m m i % r % m

m m " * ' ] " , i w a x n ^ , % ^ \ m u 1 "

1 , Wi'MiU " 4 " Mo

& & & f i^v f ' i t i nx iu r f i i j , m&imjnm-m&

128

Instructions in Experiment 4

This is an experiment on visual perception through an EEG scanner, which will

take about one hour. During your rest, we will assist you to put on an electrode cap

with some gel. The installation of the caps and the following scanning are proved to

be safe to humans. Do you agree to participate in this and the next experiments? If

yes, please sign the consent form. Thank you.

A fixation figure with 'fence' form will be first presented at the centre of the

screen for about 1 second. After the fixation figure disappears, two Chinese

characters will be simultaneously presented at the left and ride sides of the figure

respectively. After the presentation, a mask consisting of random dots will cover the

Chinese characters immediately. You are asked to determine whether the two

Chinese characters are exactly the same character. If identical, please use your

left/right thumb to press the button ' 1' and if not, please use your another thumb to

press '4' button on the 4-key board. You are also required to respond to what first

comes to your mind as quickly and as correctly as possible. If you cannot clearly

identify the characters, you can give a decision based on your own judgement but be

sure you do not miss any response. Before you give your response, please try your

best not to move your head and eyes. In the absence of stimuli, you can slightly blink.

And now you will be given a series of practice trials to adapt the tests. (Translation

from Chinese)

129

W££o ^ - ^ i 5 M ; t # J n ^ - ^ M o tmM, i m

jm" i " M; « ; m im" 4 " tt=

^ W M l M I t , ^ r T « , {Si*

^ ^ i p s j t A A o

130

Instructions in Experiment 5

I his is a target searching test through an EEG scanner. The whole experiment

will take about one hour. During the preparation for the experiment, we will equip

an electrode cap with some gel.

The experiment consists of two parts. We will first conduct Part 1. Ten

Chinese characters are selected as stimuli, i.e., iii, H, 3 )̂ ifir, I t

and among which tfe and ^ are target stimuli and other eight characters are

standard stimuli. A cross is presented at the centre of screen to check fixation before

the test. The disappearance of the cross primes the test. If targets presented, you are

asked to press ' 1' with your left/right thumb and if standards presented, please press

'4' with another thumb, as quickly and as correctly as possible. If you cannot clearly

identify the characters, you can give a decision based on your own judgement but be

sure you do not miss any response. Before you give your response, please try your

best not to move your head and eyes. After you make a response and before the next

trail starts, you can slightly blink. And now you will be given a series of practice

trials to adapt the tests.

Part 2 is the same as in Part 1 except the stimuli. The stimuli are WM, %

$L, H, M and M, among which Sp and M are target stimuli and other

eight characters are standard stimuli. (Translation from Chinese)

131

•Ai. - t - f j f € B t A ^ 1 '>0to

mi ^ & ' i • •^ r^ $ i i ^ bj ft

Aft- ^ N mmm, i t &

? J o

^ ""I " & ' j< f t . M^J l MM£IW~&a

wii#ini'/'h 't'w(mTw.¥, gp.- n u ^ ^ mm\

mi»m&nmi i s m e w ? ^ "&" m "m», u i " n 5

i t f f l £ H S J t & " 4 " ® .

&RTEBI,

iL> ^ ^ ^ SN ^ f P f T ' o " S "

, <Hi i 1 f f i&$&!&$[&&&o &&&&&&]8M^MBBIBt^

30» ^ W M i f t f i l l t , ^ n j M , { f i i f ^ ' P I ^ A A o

— ^ 3 3 .

132

APPENDIX I

32-Chaimel Electrode Montage

©

0 ©

0 © Ml

© ©

© R ©

133

APPENDIX J1

Mean latency and amplitude of positive waves (40-80 Experiment 4 (n=37)

Electrode Latency Spot Diff Equ t p Diff

ms) across the scalp in

Amplitude Equ

Anterior Frontal Lobe

Fpl

Fp2 F7

F3

Fz

F4

F8

65.89+14.40

65.95+13.85

63.51 + 13.88

59.19+14.18

58.00+14.78

59.51 + 14.83

67.40+13.48

Left Temporal Lobe

64.54+13.17

60.16 + 13.19

60.65 + 12.61

61.41 + 10.61

58.59+12.83

60.54+ 9.91

Ft7

Fc3

T7

C3

Tp7

Cp3

Central Area

Fez 58.43 + 12.39

Cz 61.19± 10.74

Cpz 63.30+ 9.96

Right Temporal Lobe

Fc4

Ft8

C4

T8

Cp4

Tp8

55.08 + 11.77

63.41 + 13.66

59.03+ 9.98

62.49 + 11.74

60.70+10.08

57.89+12.23

Parietal-Occipital Area

P7

P3

Pz

P4

P8

01

02

Oz

57.30+11.23

58.97± 12.92

62.70 ±10.98

60.81 ±11.32

59.62+12.64

61.57 ±12.90

62.11 ±12.84

63.35 ±11.62

65.78± 15.09 0.04 0.98 2.47±2.06 2.53+2.81 0.15 0.89

62.92 ±14.58 1.09 0.28 2.36 ± 2.70 2.45 ±2.48 0.24 0.81

66.32 ±15.45 0.88 0.39 1.89 ±1.91 2.43+3.05 1.26 0.22

61.30± 14.53 0.67 0.51 1.65 + 3.16 1.95±2.68 0.54 0.59

61.84± 16.64 1.36 0.18 1.05±2.22 1.46+2.34 1.10 0.28

61.19± 15.77 0.66 0.52 1.29± 1.82 1.42+2.19 0.33 0.74

62.49±15.20 1.75 0.09 2.07±2.14 2.01 ±3.23 0.13 0.90

63.46± 15.09 0.35 0.73 1.93 ±1.86 2.12±2.51 0.50 0.62

64.32 ± 13.41 1.62 0.11 1.23 ±2.12 1.14+1.85 0.27 0.79

64.81 + 12.94 1.85 0.07 1.34± 1.63 1.84±2.04 1.36 0.18

63.51 ±11.82 0.89 0.38 1.23 ±2.14 1.38±2.17 0.42 0.68

59.30± 12.55 0.25 0.80 1.08± 1.46 1.32± 1.74 0.88 0.38

60.76 ±11.46 0.14 0.89 1.19±2.01 1.53±2.73 0.86 0.40

60.49± 15.86 0.93 0.36 1.08±2.50 1.23±2.43 0.38 0.70

61.41 ±12.47 0.12 0.91 1.64±2.35 1.78±2.52 0.34 0.74

62.70 ±11.62 0.34 0.74 2.31+2.38 2.27±2.62 0.08 0.94

60.22± 14.51 1.94 0.06 1.10±2.05 1.39±2.20 0.75 0.46

63.14± 13.73 0.09 0.93 1.97±2.24 1.94±2.89 0.07 0.94

60.97 ±12.22 1.01 0.32 1.38+2.21 1.79±2.54 1.03 0.31

61.40± 12.73 0.47 0.64 0.71 ±2.03 2.02±2.67 0.71 0.49

61.24+11.28 0.25 0.81 1.68±2.08 2.13±2.63 1.23 0.23

63.19± 13.21 2.30 0.03 1.14± 1.82 1.51+2.44 1.16 0.25

58.54± 13.14 0.50 0.62 0.69±1.47 1.13 ±1.82 1.55 0.13

59.89± 13.52 0.62 0.54 1.09±3.02 2.06±3.55 2.14 0.04

63.19 ± 11.32 0.27 0.79 1.63 ±2.70 2.06±3.05 1.04 0.31

60.65 ±11.96 0.09 0.93 1.59±2.97 2.12±3.48 1.19 0.24

60.81 ±13.42 0.58 0.57 1.13±2.05 1.06±2.01 0.27 0.79

60.49± 13.57 0.61 0.54 0.25±1.62 0.49±1.87 1.10 0.28

61.62 ± 13.94 0.23 0.82 0.34± 1.61 0-51 ± 1.90 0.77 0.45

61.24± 13.53 1.12 0.27 0.17± 1.62 0.54 ±1.91 1.76 0.09

134

APPENDIX J2

Mean latency and amplitude of Experiment 4 (w=37)

negative waves (80-160 ms) across the scalp in

Electrode Spot Diff

Latency Equ t Diff

Amplitude Equ t_

Anterior Frontal Lobe

Fpl 96.32+18.43

Fp2 95.89± 16.30

F7 94.11 ±14.83

F3 98.27 ±17.25

Fz 100.11 ±16.85

F4 98.11 ±15.80

F8 100.00 ±17.76

Left Temporal Lobe

Ft7 95.24 ±15.11

Fc3 97.24 ±16.55

T7 100.22 ±19.98

C3 100.54 ±18.60

Tp7 103.73 ±19.68

Cp3 103.15 ±18.08

Central Area

Fez 101.24 ±18.36

Cz 105.68 ±19.24

Cpz 111.19± 17.41

Right Temporal Lobe

Fc4 99.41 ±14.93

Ft8 99.95 ±18.50

C4 99.35 ±15.49

T8 97.03± 17.21

Cp4 103.68 ±17.70

Tp8 100.43 ±14.80

Parietal-Occipital Area

P7 106.59± 19.35

P3 108.92 ±18.44

Pz 113.19± 14.26

P4 110.38 ±18.37

P8 104.16± 17.33

01 111 ,78 ±21 -77

02 112.59 ±20.14

Oz 114.59 ± 18.15

100.65± 19.41

101.78± 19.34

99.24± 19.80

100.92 ±17.23

103.35± 18.55

102.59± 18.50

97.14 ± 17.55

99.57±20.73

98.86± 16.66

99,61 ± 18.92

101.68± 19.58

102.05 ±20.05

105.24± 19.58

102.49 ±17.98

106.49 ±19.48

109.57± 18.89

99.19 ± 17.46

96.49 ±18.89

100.59 ±17.06

100.81 ± 17.16

102.92± 17.69

100.38± 16.54

108.54±22.06

110.54 ± 19.30

115.19± 15.69

111 .08 ±20.17

108.70± 19.92

112.86 ±21.41

118.05 ± 18.61

117.46 ± 18.84

1.10

1.84

1.27

0.72

1.19

1.63

0.85

1.15

0.60

0.17

0.40

0.50

0.88

0.46

0.27

0.76

0.08

1.10

0.42

1.12

0.27

0.09

0.88

0.68

0.44

0.35

1.33

0.38

1.45

1.15

0.28

0.07

0.21

0.47

0.24

0.11

0.40

0.26

0.55

0.87

0.69

0.62

0.38

0.65

0.79

0.45

0.94

0.28

0.68

0.27

0.79

0.99

0.39

0.50

0.66

0.73

0.19

0.70

0.16

0.26

0.54±2.39

0.24±3.03

0.19 ±2.50

- 2.27±4.84

-2.08 ±2.90

- 1.73 ±2.74

0.37±2.73

- 0.16±2.19 - 1.97 ±2.62

- 1.43 ±2.13

- 2.34±2.91

- 2.16 ±2.10 - 3.36 ±2.98

- 2.50±2.94

-2.47 ±2.93

- 3.04±3.33

- 2.18 ±2.62

-0.21 ±2.73

- 2.37±2.73

-1.34±2.36

-2.93 ±2.79

- 2.24±2.15

- 3.57±2.62

- 5.16 ±4.62

- 5.49 ±4.19

- 4.12±3.96

-2.73 ±2.88

- 3.15 ±2.39

-3.06 ±2.29

- 3.56 ±2.73

0.19 ± 3.47

-0.20 ±3.00

0.57±3.60

- 1.60 ±2.80

- 1.98±2.94

- 1.69 ±2.82

- 0.17±3.83

-0.01 ±3.24

-1.75 ±2.60

-1.12 ±2.50

-1.97 ±2.68

-2.18 + 1.96

-3.17±3.10

-2.36 ±2.75

-2.26 ±2.84

-3.04±3.32

-2.12±2.63

-0.67±3.60

-2.22 ±2.80

-1.57 ± 3.31

-2.69 ±3.13

-2.68±2.41

-3.48 ±3.07

-4.76 ±5.34

-5.00±4.55

-4.01 ±4.88

-3.17±2.76

-3.22 ±2.97

-3.24 ±2.81

-3.52±3.20

0.88

1.00

0.71

0.76

0.26

0.13

0.99

0.35

0.67

0.97

1.06

0.14

0.58

0.37

0.60

0.01

0.18

0.97

0.45

0.53

0.60

1.36

0.38

0.89

1.09

0.24

1.80

0.27

0.80

0.19

0.38

0.33

0.48

0.46

0.79

0.90

0.33

0.73

0.51

0.34

0.30

0.89

0.56

0.72

0.55

0.99

0.86

0.34

0.66

0.60

0.55

0.18

0.71

038

0.28

0.81

0,08

0.79

0.43

0.85

135

Electrode Spot Sym

Amplitude Asym t P Sym

Latency Asym t p

Anterior Frontal Lobe Fpl -1.23 ± 1.72 -1.24 ± 2.96 0.03 0.98 105.87± 15.61 111 .20 ± 15.62 2.01 0.05 Fp2 -1.59 ±1.76 -1.51 ±2.49 0.19 0.85 106.20± 15.49 106.13 ± 13.62 0.02 0.98 F7 -1.52 ±1.11 -1.51 ± 1.26 0.06 0.95 106.07± 15.62 109.53 ±14.08 1.20 0.24 F3 -1.78± 1.88 -2.50±3.60 0.93 0.36 107.33 ±14.23 110.30± 14.05 1.01 0.32 Fz -2.16 ±1.98 -2.23 ±2.67 0.15 0.88 108.93 ±15.68 107.27 ±14.91 0.52 0.61

F4 -1.82± 1.78 -2.10 ± 2.17 0.66 0.52 106.73 ± 15.14 106.07± 15.16 0.20 0.84

F8 -1.46 ± 1.31 -1.49 ± 1.79 0.08 0.94 103.20± 16.28 103.87± 14.24 0.26 0.80

Left Temporal Lobe Ft7 -1.77+1.11 -1.74± 1.25 0.08 0.93 105.67± 15.54 107.40± 15.71 0.53 0.60

Fc3 -1.85 ± 1.27 -1.94±1.60 0.27 0.79 100.87± 14.58 106.67 ± 16.38 1.54 0.13

T7 -1.71 ±0.79 -1.97 ± 2.01 0.64 0.53 103.33 ±13.34 107.93 ±15.18 1.62 0.12

C3 -1.78 ± 1.21 -1.59 ± 1.76 0.56 0.58 96.53 ±14.90 97.67± 14.33 0.28 0.78

Tp7 -1.55 ± 0.82 -1.51 ± 1.27 0.15 0.86 98.55 ±16.26 103.87 ±18.75 1.37 0.18

Cp3 -1.47 ± 1.02 -1.35 ± 1.77 0.40 0.69 97.47 ±16.58 97.60± 18.78 0.03 0.98

Central Area Fez -2.64+1.96 -2.79 ±2.28 0.39 0.70 102.47 ±15.49 104.73 ±16.50 0.61 0.55

Cz -2.27± 1.68 -2.26 ±2.45 0.02 0.98 98.53 ± 15.51 98.87± 14.53 0.09 0.93

Cpz -1.61 ±1.31 -1.68±2.32 0.19 0.85 97.93 ±15.22 94.27± 14.33 1.07 0.29

Right Temporal Lobe Fc4 -2.11 + 1.56 -2.27 ±1.96 0.40 0.69 102.53 ±15.77 100.60± 13.46 0.61 0.55

Ft8 -1.60± 1.30 -1.82 ±1.31 0.75 0.46 105.93 ±15.59 101.07± 12.03 1.56 0.13

C4 -1.88 ± 1.60 -1.64 ±2.90 0.43 0.67 98.40 ±15.65 98.27 ±16.54 0.04 0.97

T8 -1.73 ± 1.13 -1.77 ± 1.53 0.15 0.88 102.87 ±17.78 99.07 ±15.72 0.87 0.39

Cp4 -1.23 + 1.22 -1.05 ±2.14 0.41 0.69 92.07 ±16.55 94.47 ±17.01 0.79 0.44

Tp8 -1.28 ±1-16 -1.67 ± 1.26 1.55 0.13 104.53 ±21.17 93.13 ± 19.80 1.43 0.16

Parietal-Occipital Area P7 -1.31 + 1.05 -1.24 ±1.29 0.23 0.82 105.73 ±25.27 107.80 ±25.53 0.49 0.63

P3 -0.95 ±1.61 -0.93 ±2.60 0.04 0.97 99.07 ±21.85 100.20 ±22.73 0.28 0.78

Pz -1.35 ±1.32 -1.11 ±2.18 0.49 0.64 94.00 ±16.02 99.00± 19.51 1.25 0.22

APPENDIX J3

r targets across the scalp in Experiment 5 (n=3Q)

t Sym Latency Asym t

Fc3

T7

C3

Tp7

Cp3

-1.85± 1.27

-1.71+0.79

-1.78+1.21

-1.55 + 0.82

-1.47+ 1.02

Central Area Fez -2.64+1.96

-2.27± 1.68

-1.61 + 1.31

Cz

Cpz

Right Temporal Lobe Fc4 -2.11 + 1.56

Ft8 -1.60+1.30

C4 -1.88+1.60

T8 -1.73 + 1.13

Cp4 -1.23 + 1.22

Tp8 -1.28 + 1.16

Parietal-Occipital Area -1.31 + 1.05 P7

P3

Pz

P4

P8

01

02

Oz

-0.95 + 1.61

-1.35 + 1.32

-0.73 + 1.61

-1.19 + 1.50

-1.62+1.43

-1.66 + 1.55

-1.61 + 1.58

-1.94+1.60

-1.97+2.01

-1.59+1.76

-1.51 ± 1.27

-1.35 ± 1.77

-2.79 + 2.28

-2.26 + 2.45

-1.68 + 2.32

-2.27+1.96

-1.82+1.31

-1.64 + 2.90

-1,77+1.53

-1.05+2.14

-1.67 + 1.26

-1.24 + 1.29

-0.93+2.60

-1.11+2.18

-0.62+2.74

-0.73 + 1.38

-1.40+2.30

-1.40 + 2.24

-1.63 + 2.07

0.03

0.19

0.06

0.93

0.15

0.66

0.08

0.08

0.27

0.64

0.56

0.15

0.40

0.39

0.02

0.19

0.40

0.75

0.43

0.15

0.41

1.55

0.23

0.04

0.49

0.20

1.57

0.47

0.55

0.05

0.98

0.85

0.95

0.36

0.88

0.52

0.94

0.93

0.79

0.53

0.58

0.86

0.69

0.70

0.98

0.85

0.69

0.46

0.67

0.88

0.69

0.13

0.82

0.97

0.64

0.84

0.13

0.65

0.59

0.96

105.87 + 15.61

106.20+15.49

106.07+15.62

107.33 + 14.23

108.93 + 15.68

106.73 + 15.14

103.20+16.28

105.67 + 15.54

100.87+14.58

103.33 + 13.34

96.53 + 14.90

98.55 + 16.26

97,47+16.58

102.47+15.49

98.53 + 15.51

97.93 + 15.22

102.53 ±15.77

105.93 + 15.59

98.40+15.65

102.87+17.78

92.07+16.55

104.53+21.17

105.73+25.27

99.07+21.85

94.00+16.02

101.93 + 24.94

110.87 + 27.30

124.87+22.33

124.80+21.56

124.73+21.93

111.20 + 15.62

106.13 + 13.62

109.53 + 14.08

110.30 + 14.05

107.27+14.91

106.07+15.16

103.87 + 14.24

107.40+15.71

106.67+16.38

107.93 + 15.18

97.67 + 14.33

103.87 + 18.75

97.60 + 18.78

104.73 + 16.50

98.87 + 14.53

94.27+14.33

100.60+13.46

101.07+12.03

98.27 + 16.54

99.07 + 15.72

94.47+17.01

93.13 + 19.80

107.80+25.53

100.20+22.73

99.00+19.51

101.40 + 23.76

112.67 + 25.40

118.87+23.65

115.87 + 24.06

118.67+23.07

2.01

0.02

1.20

1.01

0.52

0.20

0.26

0.53

1.54

1.62

0.28

1.37

0.03

0.61

0.09

1.07

0.61

1.56

0.04

0.87

0.79

1.43

0.49

0.28

1.25

0.13

0.41

1.45

1.89

1.41

0.05

0.98

0.24

0.32

0.61

0.84

0.80

0.60

0.13

0.12

0.78

0.18

0.98

0.55

0.93

0.29

0.55

0.13

0.97

0.39

0.44

0.16

0.63

0.78

0.22

0.85

0.69

0.16

0.07

0.17

136

t P Sym

1.69 0.10 196.47 ±34.52 1.33 0.19 193.20 ± 33.24 2.59 0.02 185.13 ±23.54 2.26 0.03 184.46 ±24.99 1.96 0.06 184.33 ± 21.01 2.48 0.02 187.00±23.96 1.28 0.21 183.40 ±23.82

2.45 0.02 187.00 ±25,30 3.21 0.01 183.73 ±21.93 1.47 0.15 187.80 ± 26.62 1.98 0.06 181.67 ± 23.34 0.01 0.99 196.60 ±40.23 0.25 0.81 190.87 ±29.43

APPENDIX J4 amplitude of P2 for targets across the scalp in Experiment 5

Fpl Fp2 F7 F3 Fz F4 F8

P7 P3 Pz P4 P8 01 02 Oz

Amplitude Asym t Sym Asym

Latency

10.41 ±3.09 10.01 ±2.99 8.92 ±2.44

10.70 ±3.35 11.27 ±3.77 10.66 ±3.57 9.16 ±2.81

Left Temporal Lobe Ft7 7.65 ±2.19 Fc3 10.07 ±3.16 T7 5.65 ±2.02 C3 8.06±2.75 Tp7 2.70 ±1.79 Cp3 5.84±2.12

Central Area Fez 10.91 ±3.82 Cz 10.22 ±3.32 Cpz 8.87±2.97

Right Temporal Lobe Fc4 9.90 ±3.31 Ft8 7.75 ±2.57 C4 8.15 ±3.17 T8 5.84 ±2.10 Cp4 6.33 ±2.79 Tp8 3.13 ± 2.20

Parietal-Occipital Area 0.55 ±1.79 3.66±2.70 5.92 ±2.70 4.32+3.92 1.00 ±2.62

- 0.26± 1.91 0.02 ±1.96 0.01 ±2.10

9.41 ±3.90 9.47 ±3.22 8.06±2.73 9.66 ± 2.83

10.63 ±3.44 9.91 ±3.07 8.73 ±2.69

6.93 ±2.58 9.29 ±2.83 4.92±3.04 7.59±2.84 2.70 ±1.74 5.75 ±2.74

10.11 ±3.22 9.74±3.51 8.58 ±3.33

9.18 ±3.16 7.18 ±2.39 8.27±4.07 5.71 ±2.31 6.71 ±3.55 3.36 ±2.01

1.55 ±1.99 4.63 ±3.80 6.53 ±3.14 5.40 ±4.75 2.09±2.59 0.65 ±3.07 0.80±2.92 0.29±2.61

1.69 1.33 2.59 2.26

1.96 2.48 1.28

2.45 3.21 1.47 1.98 0.01

0.25

2.85 1.39 0.71

2.43 1.85 0.23 0.47 0.74 0.83

3.71 1.75 1.34 1.68

3.41 1.60

1.61 0.69

0.10 0.19 0.02 0.03 0.06 0.02

0.21

0.02 0.01

0.15 0.06 0.99 0.81

0.01

0.17 0.49

0.02 0.07 0.82

0.64 0.46 0.42

0.01 0.09 0.19 0.10

0.01 0.12 0.12 0.50

196.47 ±34.52 193.20 ±33.24 185.13 ±23.54 184.46 ±24.99 184.33 ±21.01 187.00±23.96 183.40 ±23.82

187.00 ±25,30 183.73 ±21.93 187.80 ± 26.62 181.67 ± 23.34 196.60 ±40.23 190.87 ±29.43

183.07 ± 21.53 183.67±24.80 182.80 ±29.00

188.40 ±25.77 184.33 ±26.43 190.00±29.82 191.07±33.18 203.20±38.35 218.20±43.43

179.60 ±47.59 204.33 ±48.01 204.07±44.60 220.40 ±44.47 230.40±49.35 201.13 ± 50.41 212.27±47.84 201.87 ±49.18

190.40 ±31.52 190.53 ±31.05 185.13 ±25.24 187.46 ±27.40 185.80 ±24.85 190.33 ±29.54 188.13 ± 27.73

188.27 ±30.90 183.40 ±21.20 191.60 ±33.66 197.53 ±40.13 199.66 ±47.24 203.53 ±42.31

185.33 ±23.53 191.00 ±34.20 198.13 ±43.46

189.80+28.14 184.20 ±22.59 196.20 ±37.47 201.67 ±39.21 208.07±46.01 221.07±48.66

198.47 ±53.05 214.27±49.13 203.60±49.30 218.80 ±47.85 217.27 ±50.40 191.13 ±52.23 208.93 ±45.63 204.93 ±50.50

0.92 0.41 0.00 0.89 0.62 0.77 0.99

0.37 0.69 1.00 0.38 0.54 0.45 0.33

0.21 0.84 0.22 0.83 0.85 0.41 2.18 0.03 0.39 0.70 1.59 0.12

0.97 0.34 1.52 0.14 2.56 0.02

0.31 0.04 1.23 1.43 0.72 0.36

2.22

1.15 0.07 0.21 1.16

1.15 0.37 0.33

0.76 0.97 0.23 0.16 0.48 0.72

0.04 0.26 0.95 0.83 0.26 0.26 0.72 0.74

137

Mean latency and («=30)

APPENDIX J5 amplitude of N2 for targets across the scalp in Experiment 5

Symm Amplitude Asym t

Latency Sym Asym t p

Anterior Frontal Lobe 0.43+4.33 0.05+4.49

-0.67 + 3.30 - 1.35+4.16 -2,65+4.75 - 1.10+4.28 -0.36 + 3.40

Left Temporal Lobe Ft7 -0.98 + 2.58

- 1.21+3.52 - 1.32+2.35 -0.73 + 3.15 - 1.72+1.58 -0.49 ±2.65

Central Area Fez - 2.50±4.90 Cz -0.70 ±4.42 Cpz 0.29 ±3.87

Right Temporal Lobe Fc4 - 1.06 ±3.88 Ft8 -0.69 ±2.69

-0.35 ±3.74 -0.93 ±2.04 0.16 ±2.86

- 1.28 ±2.34

Fpl Fp2 F7 F3 Fz F4 F8

Fc3 T7 C3 Tp7 Cp3

C4 T8 Cp4 Tp8

Parietal-Occipital Area P7 P3 Pz P4 P8 01 02 Oz

- 3.84±2.14 - 1.73 ±2.79 -0.74+2.42 - 1.15 ±2.68 -2.93 ±2.60 -3.46 ±2.03 -3.04 ±2.23 - 3.00±2.23

- 0.47±5.37 - 0.06±4.44 - 0.96±3.71 - 2.37±4.61 -2.44 ±4.85 - 1.25 ±3.89 0.20±3,36

-1.15±2.86 -1.10 ± 3.61 -1.78 ±3.23 - 0.69 ± 3.31 - 2.26±2.30 -0.71 ±3.27

-2.77 ±4.93 - 1.08 ±4.84 -0.55 ±4.29

- 0.95±3.75 -0,23 ±2.54 0.05 ±4.61

-0.59 ±2.63 0.32±3.70

- 1.40 ± 1.76

- 4.17±2.43 - 1.69 ± 3.73 -0.94±3.85 - 0.78±3.92 -2.62 + 2.54 - 3.37±2.66 - 2.63±2.58 -2.91 ±2.44

0.96 0.17 0.53 1.22

0.47 0.26

1.26

0.41 0.24 0.78 0.10

1.54 0.56

0.56 0.80 1.76

0.24 1.24 0.68

0.90 0.27 0.40

0.86 0.06 0.36 0.52 0.82 0.20 0,95 0.24

0.38 0.85 0.60 0.23 0,64 0.80 0.22

0.23 0.50 0.37 0.79 0.69

0.40 0.95 0.73 0.60 0.42 0.88 0.35 0.81

342.40 ±36.58 340.33 ±40.73 323.40±29.27 312.54±21.91 311.47 ±21.83 313.00±22.00 320.80 ±35.32

335.20 ±53.76 333.33+53.79 319.93 ±47.71 325.00 ±29.72 315.93 ±32.19 319.80 ±38.19 318.87 ±50.23

0.74 0.62

0.44 2.02

0.69 0.92 0.42

0.46 0.54 0.66

0.04 0.50 0.37 0.68

0.69 319.20 ±25.97 325.47±40.92 0.92 0.37 0.81 0.44 0.92 0.14 0.58

0.58 0.43 0.09

306.33 ±26.79 315.93 ±31.56 305.60 ±27,64 304.00±41.73 294,33 ±37.48

3 04.20 ±21.22 300.33+24.93 291.87 ± 32.19

310.13 ±37.61 322.87±35.9 5 305.87 ±37.23 299.80±48.28 294.00 ±44.74

307.87 ± 37.55 299.80 ±40.8 8 274.93 ±42.00

0.53 1.03 0.04 0.41 0.05

0.57 0.07 1.88

0.60 0.31 0.97 0.69 0.96

0.58 0.95 0.07

0.82 304.20±21.52 304.93 ±38.70 0.11 0.92 315.87+33.49 301.87 + 27.05 304.73 ±38.63 289.47 ±34.11 295.47 ±39.07

266.13 ±39.63 263.47±37.78 270,53 ±35,53 268.13 ±36.36 278.80±42.62 264.13 ±34,32 266.00±49.58 268.93 ±47.85

3 07.67 ±50.02 300.07±41.34 298.13 ±58.81 286.60±50.30 289.73 ±57,13

293.93 ±39.52 272.60 ±40,20 276.27±40.11 279.60±48.61 296,00 ±50.24 291.20 ±30.51 292.20 ±48.22 279.87±28.62

0.99 0.25 0.80 0.37 0.65

2.72 1.42 0.90 1.40 1.98 3.73 2.50 1.34

0.33 0.81 0.43 0.72 0.52

0.01 0.17 0,39 0.17 0.06 0.01 0.02 0.19

138

Mean latency and (»=30)

APPENDIX J6 amplitude of P3 for targets across the scalp in Experiment 5

Symni Amplitude Asym

Anterior Frontal Lobe Fpl 6.86±4.44 Fp2 7.16 ±4.64 F7 7.06 ±3.93 F3 12.27 ±5.04 Fz 14.62 ±5.03 F4 12.63 ±5.14 F8 7.65 ±3.75

Left Temporal Lobe Ft7 7.83 ±3.29 Fc3 14.69 ±4.60 T7 8.79±3.03 C3 15.62 ±4.45 Tp7 7.79 ±2.71 Cp3 15.37 ±4.05

Central Area Fez 17.53 ±5.54 Cz 19.18 ±5.47 Cpz 19.16 ±4.94

Right Temporal Lobe Fc4 15.15 ±5.24 Ft8 8.03 ±3.34 C4 15.72 ±4.91 T8 8.69 ±3.14 Cp4 15.10 ±4.26 Tp8 8.39 ±3.18

Parietal_Occipital Area P7 5.66 ±2.40 P3 12.71 ±3.70 Pz 15.48 ±4.49 P4 12.57 ±4.24 P8 5.70±2.87 01 3.17 ± 2.17 02 3.16 ±2.38 Oz 3.50±2.48

Latency Sym Asym t p

7.11 ±4.15 0.27 7.51 ±3.11 0.61 6.94±3.78 0.18

11.28 ±4.60 1.04 14.41 ±4.90 0.31 11.98 ±4.07 0.93 7.79 ±2.77 0.34

7.44±3.67 14.24 ±4.73 8.24±3.47

15.12±4.43 7.39 ±2.91

14.90 ±4.73

16.82 ±5,54 18.17 ±5.60 18.01 ±5.51

14.40 ± 5.01 7.70±2.30

15.22 ±5.33 8.27±2.64

14.63 ±4.85 7.86 ± 2.35

5.86±2.82 12.97 ±5.09 15.07 ±5.53 12.74±5.20 6.10 ±2.64 3.23 ±2.58 3.55 ±2.57 3.63 ±2.54

0.74 0.83 1 . 1 1 0.96 1.26

0.80

1.01 1.50 1.83

1.14 0.77 0.78 1.04 0.81

1.64

0.74 0.38 0.67 0.26 1.42 0.88 0.98 0.33

0.79 0.55 0.86 0.31 0.76 0.36 0.74

0.47 0.41 0.27 0.35 0.22 0.43

0.32 0.15 0.08

0.26

0.45 0.44 0.31 0.42 0.11

0.47 0.71 0.51 0.80 0.17 0.39 0.34 0.75

409.53 ±81.89 408.47± 80.91 468.20 ±45.11 456.46±40.96 447.60 ±40.06 450.20 ±40.35 445.47 ±59.99

467.53 ±41.05 459.27±37.84 472.00 ±35.91 467.40±29.52 471.87 ±35.80 469.53 ±30.17

454.00 ±38.40 458.80±36.54 465.33 ±29.77

459.87±39.24 465.87±40.27 463.20 ±31.75 471.47 ± 35.96 466.60±30.39 462.47 ±34.93

471.40 ± 36.59 470.13 ±32.73 462.93 ±32.27 462.00 ±31.74 456.93 ±39.15 459.47±42,30 449.53 ±47.12 460.67±46.06

388.67 ± 80.83 397.80±73.36 455.27±66.85 462.69±50.84 456.00±43.31 457.73 ±42.43 451.86 ±68.94

480.33 ±40.31 460.27±39.82 475.47 ±39.12 472.53 ±34.14 468.07 ±32.84 467.40 ±31.58

457.53 ±40.66 465.87±41.14 474.00 ±40.13

463.00±44.68 460.67±66.83 465.00±40.59 463.87±49.96 462.73 ±34.37 457.60 ±52.20

465.00±31.79 457.40±35.33 461.33 ±31.91 453.00 ±29.04 453.60±37.92 451.80 ±44.42 440.93 ±48.27 451.00 ±47.09

1.38 0.90 1.26 0.57 1.14 0.90 0.63

0.17 0.51 0.97 0.59 0.41

0.61 1.25 1.43

0.44 0.42 0.28 0.71 0.62 0.47

0.93 1.98 0.31 1.68

0.46 0.80

1.08 1.09

0.18

0.38 0.22

0.58 0.26 0.38 0.54

0.10

0.86 0.62 0.34 0.56 0.68

0.55 0.22

0.16

0.66 0.68

0.78 0.49 0.54 0.64

0.36 0.06

0.76 0.10 0.65 0.43 0.29 0.28

139

Mean latency and 5 (n=37)

APPENDIX J7 amplitude o fNl for standards across the scalp in Experiment

Anterior Frontal Lobe Fpl -1.09+1.56 Fp2 -1.03 + 1.60 F7 -0.95 + 1.82 F3 -1.60+1.53 Fz -2.24+1.87 F4 -1.70+1.60 F8 -0.82+1.65

Left Temporal Lobe Ft7 -1.23 + 1.29 Fc3 -1.85 + 1.43 T7 -1.26+1.06 C3 -1.66± 1.37 Tp7 -1.67+1.30 Cp3 -1.31+1.27

Central Area Fez -2.70+1.97 Cz -2.25 + 1.79 Cpz -1.51 ±1.59

Right Temporal Lobe Fc4 -1.95 + 1.36 Ft8 -0.90+1.69 C4 -1.70+1.31 T8 -1.14+1.56 Cp4 -1.29+1.35 Tp8 -1.51 + 1.42

Parietal-Occipital Area P7 -4.45 ±2.67 P3 -1.97 ±2.29 Pz -1.11 ±1.49 P4 -2.27 ±2.43 P8 -4.27±2.81 01 -3.28+1.81 02 -3.18± 1.99 Oz -2.87 ±2.09

Amplitude Latency Symm Asym t p Sym Asym t_

-1 -09± 1.90 -1.41 ±2.06 -0.93 + 1.62 -1.60 ±2.27 -2.37 ± 1.85 -1.84± 1.74 -0.96 ±1.62

-1.21 ±1.29 -1.75 ±1.49 -1.27 ± 1.21 -1.47 ± 1.38 -1.59 ± 1.44 -1.19 ± 1.29

-2.71 ±2.04 -2.13 ±1.79 -1.37 ± 1.53

-1.92± 1.45 -1.13 ± 1.45 -1.56 ± 1.41 -1.29± 1.39 -1.14± 1.41

0.03 1.70 0.14 0.00 0.67 0.88

0.60

0.14 0.52 0.07 1.07 0.55 0.73

0.05 0.60 0.74

0.18

1.18 0.72 0.88

0.70

0.98 0.10

0.89 1.00 0.51 0.39 0.56

0.89 0.61

0.95 0.29 0.59 0.47

0.96 0.56 0.47

0.86

0.24 0.48 0.39 0.49

108.54± 14.98 107.57± 13.45 107.35 ± 12.25 105.46± 12.49 107.08 ±14.22 105.84± 13.16 104.65 ±14.49

105.89 ±12.73 104.49 ±12.09 105.24 ±21.96 98.70± 13.03

129.84±41.82 101.41 ±26.93

105.19± 14.16 99.62 ±12.28 97.83 ±21.38

102.70± 14.86 102.92± 13.74 101.57 ±21.83 102.49+21.25 104.97±32.84

107.84+14.00 108.22± 13.50 106.81 ±13.80 110.11 ±15.22 109.35 ±14.25 109.51 ±14.50 105.56± 12.13

105.46 + 14.44 106.43 ±13.96 109.03 ±21.13 102.76 ±14.46 128.11 ±37.92 108.76 ±26.94

107.57 ±14.29 101.14± 12.21 99.14+11.38

105.51 + 13.89 101.89 ±13.10 99.03 ±11.95

102.81 ±13.80 106.38 ±30.41

0.30 0.40 0.29 2.55 1.10

1.85 0.54

0.19 1.02 0.87 1.36 0.47 1.46

1.13 0.85 0.33

1.40 0.73 0.73 0.10 0.32

-4.85 ±2.59 -2.09 + 2.49 -1.03 ±1.49 -1.96±2.62 -4.55 ±2.95 -3.57 ±1.76 -3.04±2.50 -2.70±3.10

3.04 0.60

0.55 1.26 1.46 1.47 0.48 0.42

0.01 0.56 0.59 0.22 0.15 0.15 0.63 0.68

166.05 ±22.92 144.81 ±42.35 114.05 ±41.82 148.86 ±41.01 169.67± 18.92 168.92+16.96 169.68± 15.36 167.30 ±18.20

165.78+21.70 143.41 ±38.01 109.46 ±33.25 152.16 ±37.35 170.76 ±17.27 167.95 ±13.56 165.41 ±18.42 166.43 ± 15.52

0.76 0.69 0.78 0.02 0.28 0.07 0.60

0.85 0.32 0.39 0.18

0.64 0.15

0.26

0.40 0.75

0.17 0.47 0.47 0.92 0.75

-1.46 ± 1.27 0.27 0.79 138.22±39.93 123.08±39.15 2.00 0.05

0.22 0.26

0.79 0.64 0.30 0.50 1.09 0.48

0.83 0.80

0.44 0.53 0.77 0.62 0.28 0.64

140

1 5

APPENDIX J8 Mean latency and amplitude of P2 for standards across the scalp in Experiment 5 («=37)

Symm Anterior 1

Fpl

Fp2

F7

F3

Fz

F4

F8

:rontal Lobe

8.03 ±2.63 7.99 + 2.77 7.38 + 2.22 8.62 ±2.54 8.53 + 2.78 8.31 ±2.55 7.39 + 2.31

Left Temporal Lobe Ft7

Fc3 T7

C3

Tp7

Cp3

Fe4

FtS

C4

T8

Cp4

Tp8

7.64 ±2.39 6.34 ±2.17 6.23+2.39 4.46 ±1.75 4.91 + 1.96 2.25 + 1.22

F7 P3 Pz

P4

P8

01 02 Oz

0.91 ±1.52 3.79 ±2.35 4.99 ±2.14 3.83 ±2.94 1.62 ±1.92 0.25 ±1.51 0.57+1.83 0.37 ±1.72

Amplitude Asjap t_

6.11 ±2.08 7.67 ±2.44 4.34 ±1.83 5.99 ±2.22 1.94 ±1.44 4.63 ±1.81

Central Area

Fez 8.19 ±2,84 Cz 7.62 ±2.68 Cpz 6.88 ±2.32

Right Temporal Lobe

Parietal-Occipital Area

8.83 ±2.96 8.46 ±3.10 8,05 ±2.29 9,68±3.14 9.64 ±3.09 9.37±3.00 7.88±2.70

6.72 ±2.25 8.74±2.65 4.93 ±2.03 6.98 ±2.58 2.32 ±1.79 5.13 + 2.12

9.41 ±3.17 8.88 ± 2.98 7.66 ±2.63

8.64±2.80 6.76 ±2.46 7.21 ±2.81 4.95 ±2.05 5.34 ±2.42 2.56 + 1.52

1.11 ± 1.48 3.66 ±2.63 4.98 ±2.33 3.94 ±3.31 1.73 ±2.19 0.46 ±1.91 0.99±2.52 0.79 ±3.16

Sym Asym Latency

t

3.31 1.49 3.54 3.61 4.82 4.67 1.64

3.90 4.97 3.48 4.89 1.99 2.97

4.71 5.79 3.34

4.64 1.38 4.33 2.39 1.69 1.61

1.04 0.50 0.05 0.41 0.43 1.09 1.50 1.16

0.01

0.15 0.01

0.01

0.01

0.01

0.11

0.01

0.01

0.01

0.01

0.05 0.01

0.01

0.01

0.01

0.01

0.18

0.01

0.02

0.10

0.12

0.30 0.62

0.96 0.68

0.67 0.28

0.14 0.26

185.30±23.32 182.97 ±21.68 182.11 ± 19.61 182.86± 19.50 182.86 ±19.25 183.95 ±19.38 183.84±22.07

183.73 ±23.89 182.76 ± 20.14 186.11 ±32.47 186.27 ±30.79 231.62 ±50.46 207.67 ±51.90

181.24± 18.59 180.32 ±20.32 195.89 ±43.65

187.24 ±24.22 180.65 ±22.23 199.14 ±40.80 184.97 ±27.55 216.65 ±51.39 231.62 ±50.47

232.11 ±55.33 227.51 ±51.11 213.67 ± 55-25 225.41 ±55.90 236.00 ± 54.18 217.89 ± 53.63 232.59 ±48.57 217.89 ± 52.60

183.03± 18.47 182.16± 17.36 184.22±20.36 183.46± 18.68 182.76 ±17.99 183.24± 18.13 183.89±20.54

184.60 ±22.42 182.65 ±18.45 188.97+29.46 186.16 ± 26.54 228.38±48.88 207.14 ±41.18

181.51 ±16.48 184.54 ± 23.17 190.00 ±31.86

184.54 ±20.29 185.30±23.91 188.22±28.44 188.81 ±29.69 206.65±43.75 228.37±48.88

222.22 + 60.48 227.95 ±47.88 203.62 ±44.59 223.84±49.20 235.89±54.17 218.43 ±56.43 222.97+52.25 220.38±54.88

0.70 0.37 0.82 0.28 0.06 0.36 0.03

0.28 0.06

1.05 0.03 1.40 0.06

0.21 1.47 1.24

0.75 1.63 2.08 0.76 1.75 0.48

1.14 0.06

1.28

0.24 0.02

0.06 1.43 0.35

0.49 0.71 0.42 0.78 0.96 0.72 0.98

0.78 0.95 0.30 0.98 0.17 0.95

0.84 0.15 0.23

0.46 0.11

0.05 0.45 0.09 0.64

0.26

0.95 0.21 0.81 0.99 0.95 0.16

0.73

141