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Challenges to Piaget

From Method to Theory

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Outline

• Theories– Nativism v empiricism– Constructivism

• Methods– Experimental Design– Experimental Techniques

• Spatial Knowledge

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Nativists versus Empiricists

• Empiricists– Mind as a Blank Slate– Behaviorism– Environment shapes development– Infant has no active role in

development?

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Constructivism

• Piaget Theory of Cognitive Development– Innate operations allow the child to structure

interactions with environment, so that the child constructs knowledge about the world

– Theory thus has a (small) genetic component and an environmental component

– Child plays an active part in development

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Nativism

• Nativists – abilities develop with (perhaps trivial) environmental contribution – maturation– Preformationism – structures for

behaviour are present from birth– Predeterminism – structures develop in

a predetermined sequence

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Experimental Methods

Descriptive research • consists of simply observing children and

recording their behaviorsCorrelational research • aims to describe the association between two

variablesExperimental research • aims to show a causal relationship between

one variable and another

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Experimental Methods

• How have changes in methods caused us to think differently about development?– Peripheral sources of knowledge

• Outside in

– Central sources of knowledge• Inside out

– Tacit knowledge

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Experimental Methods

• Longitudinal studies measure a behavior in the same subject at different ages

• Advantages of longitudinal designs:– Provide estimates of stability of behavior over time– Estimate the impact of early experiences on later

behavior

• Issues in longitudinal designs:– Attrition of subjects over time (particularly ‘poor’

performers?)– Problems with repeated testing– Costly and time-consuming

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Experimental Methods• Cross-sectional studies measure a behavior in

different aged subjects at the same time point• Cross-sectional studies cannot tap into

stability of behavior (because different subjects are used)

• Cohort effect: Different age groups have different life experiences that may have profound impact on their behavior

• Cross-sequential studies combine longitudinal and cross-sectional designs

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Experimental Techniques

• What can be measured in terms of infant responses?

• Behavioural measures

• Physiological measures

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Experimental Techniques

• Spontaneous visual preference technique– Infant is presented with two visual stimuli in

left and right visual field– Infant will tend to look at one stimulus more

than the other (after controlling for side bias)– Infant can discriminate between the two

stimuli

• High amplitude sucking

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Experimental Techniques

• Habituation – decline in response to a stimulus as it is learned about

• Infant will look less at a stimulus due to habituation

• When a new stimulus is presented, failure to discriminate the difference between stimuli will result in looking times at the habituated level

• If infants do discriminate between stimuli, they should dishabituate (look more at new stimulus)

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Habituation

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Experimental Techniques

• Habituation-Novelty– Habituate infant to single stimulus, then

present habituated and new stimuli– Discrimination will lead to more looking at the

new stimulus. Failure to discriminate will result in equal looking to both.

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Paired presentation

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Experimental Techniques

• Visual preference techniques can be coded ‘online’, or recorded and coded later, or both

• Technological advances mean that eye trackers have now been developed that can be used with infants

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Physiological Measures

• Heart rate – often used in studies of attention– Heart rate declines with increases in attention

• ERP – Event related (brain) potentials– Individually evoked brain responses to

repetitive stimulation are summed and averaged

– Recorded non-invasively using surface electrodes

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ERPs

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ERPs

• ERPs result in a waveform in which positive (P) or negative (N) components can be identified

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ERPs

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ERPs - Problems

• Need correlations with behavioural measures to relate ERPs to actual behaviours/cognitions

• Repeated presentations – novel becomes familiar

• Measuring cognitive processes using ERPs has been compared to hanging a microphone over the streets of New York to find out about language -- poor spatial resolution

• BUT – exciting new method

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Methodological Differences

• Domain-general Approaches– Piaget (1954)– Studied using search tasks– End product of sensori-motor development

• Nativist Approaches– Studies using habituation and preferential

looking tasks– Product of innate domain-specific

constraints about objects and their properties

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SpelkeTwo Basic Problems

• Segmentation– The proximal visual stimulus is seamless –

how do we segregate this into (distal) objects

• Identification– Having segregated portions of the visual

input, how do we recognize these as particular coherent objects or events?

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How to Segment: Gestalt

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Gestalt Principles of Grouping

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Examples of Gestalt Groupings

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Figure-Ground Segmentation

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Evidence for Early Knowledge

• Imitation– Think about Piaget’s notion of

egocentrism.

– What does that predict about the ability to imitate from an early age?

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Imitation in 1-month old infantsMeltzoff and Moore (1983)

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Meltzoff & Moore (1994)

• 6 month old could imitate facial expression a day later

• Half infants saw adult make facial expression (e.g., stick out tongue)

• Half infants saw adult with neutral expression

• All infants saw adult next day• Infants who saw facial expression

significantly more likely to repeat facial expression

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Object Permanence and Object Concept

• Object Permanence– Baillargeon (1987)

habituated and tested as seen -->

– Control condition was the same but without the box

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Baillargeon (1987)

• Found that 4.5-month-olds discriminate the impossible event relative to possible– Even though the range

of motion of the screen was the same as during habituation

0

10

20

30

40

50

60

-6 -5 -4 -3 -2 -1 1 2 3 4

FamiliarizationImpossiblePossible

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Baillargeon (1987)

• Object Permanence– Piaget suggested that object permanence is attained by around

9 months, when they begin to search for hidden objects– Baillargeon’s results suggest that Piaget was wrong and that

some form of object permanence is available as early as perhaps 3.5 months

– That they have object permanence before they can search (which was required by Piaget)

– Suggests that this ability might be innate• Spelke hypothesizes that conception of objects as spatially bounded

entities that exist continuously in time and move through space, maintain their unity and boundaries, is innate

– Infants have “expectations” about the behavior of objects in space and time

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What do we know about objects?

• a single object can have effects through several sensory modalities (vision, hearing, touch…)

Remember inter-sensory coordination (Class 5): Meltzoff & Borton showed oral-tactile transferred to visual recognition in newborns

- the basis of this aspect of object ‘knowledge’ is present very early

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Spelke: What do infants know about objects?

Habituate Unitary Object Test Two Object Test

Kellman and Spelke (1983)

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Object Segmentation by Common Fate

• Kellman & Spelke (1983):

– 4-month-olds

dishabituate to

the two object test 0

2

4

6

8

10

12

1 3 5 7 9 -2 -4

Trials

Looking Timehabituation

Two Object

Unitary Object

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Objects cannot move through other solid objects (e.g. Spelke, 1992)

4 mth olds habituated to ball falling behind a screen:

____________ _____________

____________ _____________Plausible Event Anomalous Event

Results: looked longer at anomalous event

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Results

• Blue shows habituation• 4-mo-old infants looked longer at inconsistent event

(red dot) compared to consistent event (green)

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Results

• 2 ½-mo-olds look reliably longer at the inconsistent event

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Spelke’s Three Principles of Object Perception

• Continuity: "An object traces exactly one connected path over space and time“

• Cohesion: "objects maintain their connectedness and their boundaries as they move”

• Contact: "distinct objects move together if and only if they touch”

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Contact: Example

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Spelke's Suggestions about Initial Physical Knowledge

• Initial knowledge is innate. – Learning requires systems that parse the world

appropriately. For example, infant cannot logically make inferences about the behavior of objects until they can (1) segment objects from their contexts and (2) represent the identity of individual objects across time and space.

• Initial knowledge is domain specific. – Infants appear to have knowledge of certain principles within

the realm of physics (cohesion, contact, continuity); there are other domains in which infants lack knowledge (e.g., shadows). Infants do have knowledge in certain other realms (including number and psychology), but do not apply these physical principles there.

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Basic Terminology of Domain-Specificity

A module is:

an information-processing unit that encapsulates certain forms of knowledge and the computations on it (Fodor, 1983)

genetically specified, independently functioning hard-wired, of fixed neural architecture

a fast, autonomous, mandatory, and automatic processing system.

MODULES ARE FIXED & INFLEXIBLE

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What is a Domain?Wellman & Gelman (1992)

• innately given modular abilities (e.g. Fodor, 1983)

• modes of processing tied to particular sensory modalities

• areas of expertise

• Piaget-inspired cognitive tasks: classification, seriation and conservation

• naïve theories and concepts which carve phenomena into differing organised systems of knowledge and belief such as physics, maths, biology etc.

DOMAINS ARE NOT ALWAYS MODULES

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Domain-Specificity in Conceptual Development Theories

DOMAINDOMAIN DOMAIN DOMAIN MODULAR MODULAR

GENERALGENERAL SPECIFIC SPECIFIC VIEW VIEW

Piaget Innate Constraints Fodor

(Keil, 89)

Skinner Innate Domains Chomsky

(Carey, 86)

Bruner Foundational Theories ToMM(Sperber)

(Wellman & Gelman, 92) ToBy (Leslie, ) Innate Theories Physics

(Spelke) (Gopnik & Meltzoff, 97) Biology(Atran, 99)

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Domain General Theories

• Piaget: Innate sensory reflexes and three function processes; universal sequential stages

• Behaviourists: Innate sensory system and laws of association

• Information Processing: General processes or architectures:

– Bruner (1964) representational format develops from enactive to iconic to symbolic

– Case (1985) speed or processing or size of working memory increase developmentally

Domain-general theories have relatively few universal rules and are parsimonious and powerful

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‘Theory Theory’Gopnik & Meltzoff (1997)

“...we will argue that children’s conceptual structures, like scientists’, are theories, that their conceptual development is theory formation and change, and that their semantic development is theory-dependent” (p. 11)

Theories

Characteristics Functions

Abstract Prediction

Coherent Interpretation

Causality Explanations

Ontological commitment

Theories are dynamic and can change with counter evidence

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Theory Theory

• 3 Cognitive Processes (1997; p. 68):

– Modules

– Theories: innate theories to assign representations to out put of modules)

– Empirical generalizations: inputs not predicted by theories => theory revision

• 3 Innate Theories (domains) :

– Appearances: object permanence

– Actions: underlies theory of mind

– Object kinds: including biological kinds vs. artifacts distinction