Are phonological representations in bilinguals language

specific? An ERP study on interlingual homophones.

Journal: Psychophysiology

Manuscript ID: PsyP-2010-0391

mstype: Full-length report

Date Submitted by the

Author: 27-Dec-2010

Complete List of Authors: Carrasco-Ortiz, Haydee; Aix-Marseille University, Laboratoire de Parole et Langage Midgley, Katherine; Tufts University, Psychology Department; Aix-Marseille University, Laboratoire de Psychologie Cognitive Frenck-Mestre, Cheryl; Centre National de la Recherche Scientifique, Laboratoire de Parole et Langage; Aix-Marseille University

Keywords: Cognition < Content, Language/Speech < Content, Normal Volunteers < Groups Studied, EEG/ERP < Measures Used

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Are phonological representations in bilinguals language specific? An ERP study

on interlingual homophones.

Haydee Carrasco-Ortiz1, Katherine J. Midgley1, 2, Cheryl Frenck-Mestre1,3

1Aix-Marseille University, France

2Tufts University, USA

3Centre National de la Recherche Scientifique

Address for correspondence:

Haydee Carrasco-Ortiz

Aix-Marseille University

Laboratoire de Parole et Langage

5 avenue Pasteur

13604 Aix-en-Provence, FRANCE

elia.carrasco-ortiz@etu.univ-provence.fr

Tel. +33 442953746

Fax : +33 442953788

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Abstract

Event-related potentials (ERPs) served to investigate whether phonological representations

from both the first (L1) and second (L2) language of bilinguals are activated during silent

reading of L2 words. French-English late bilinguals and control monolingual English

speakers read Interlingual homophones (e.g., pool in English which has substantial

phonological overlap with the French word “poule”, meaning ‘chicken’) and matched control

words. Results showed a reduction in N400 amplitude in response to interlingual homophones

in comparison to control words for bilinguals, but not for English monolinguals. The reduced

N400 response to homophones in bilinguals suggests facilitation of word recognition. These

results suggest parallel activation of both L1 and L2 phonological representations when

reading silently in the L2. These findings point to a language nonspecific model for bilinguals

at the phonological level of representation.

Keywords: Bilingualism, Visual word recognition, Phonology, ERPs, Interlingual

homophones.

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INTRODUCTION

One line of research in bilingualism has focused on how bilinguals represent words

from two distinctive language systems and whether or not lexical representations in one

language activate those of the other language. The majority of current models of bilingual

word recognition are framed in an interactive language system, in which words are processed

on the basis of their orthographic, semantic and phonological similarity across languages

(Dijkstra & Van Heuven, 1998, 2002; but also see Kroll & Stewart, 1994). Indeed, there is

relatively widespread agreement that orthographic, semantic and phonological codes all play a

role in bilingual word processing. However, it is less clear how and when these lexical codes

become active and how the nature of this activation varies as a function of the consistency

across a bilingual’s two languages. The present study is focused on determining the extent to

which phonological codes become active across languages and influence bilingual word

recognition. More specifically, we examined whether words with a high degree of

phonological overlap across languages influence visual lexical processing when reading

silently in the L2 alone.

Research on bilingual visual word recognition has predominantly focused on

orthographic processes. Indeed, numerous empirical studies have shown that bilingual word

recognition can be strongly influenced by orthographic overlap, both within and across

languages (Van Heuven, Dijkstra, & Grainger, 1998; Dijkstra, Timmermans & Schriefers,

2000; Midgley, Holcomb & Grainger, 2009). Fewer studies have investigated the role of

phonological codes in bilingual word recognition (Brysbaert, Van Dyck & Van de Poel, 1999;

Dijkstra, Grainger & Van Heuven, 1999; Doctor and Klein, 1992; Duyck, 2005; Haigh and

Jared, 2007; Lemhofer and Dijkstra, 2004). Those that have, have suggested that word

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recognition is largely affected by phonological overlap across languages. However, the nature

of these cross-linguistic effects is not entirely clear; the behavioral data obtained in previous

research involving single word paradigms has presented contradictory evidence (Dijkstra et

al.,1999; Haigh and Jared, 2007; Lemhofer and Dijkstra, 2004). Whether phonological

overlap across languages facilitates lexical identification in L2 or instead inhibits recognition

due to the activation of competing interlingual phonological codes is still an open question.

The aim of the current study was to present electrophysiological data as a means to determine

the impact of cross-linguistic phonological codes on bilingual word processing.

To address the question of phonological processing during bilingual visual word

recognition, investigators have relied on interlingual homophones. An interlingual

homophone is a lexical letter string, the pronunciation of which is much alike in the

bilingual’s two languages but does not have the same spelling or meaning in the two (e.g.

pool in English and “poule” in French, which means chicken). The unique characteristics of

interlingual homophones enable one to examine the effect of phonology independent of

semantic overlap and over and above purely orthographic overlap. Evidence of between-

language phonological interference comes from studies conducted by Dijkstra et al. (1999)

and Doctor and Klein (1992). These authors found that bilinguals processed visually

presented interlingual homophones more slowly than matched control words in a lexical

decision task. These results suggest that bilinguals activated phonological representations of

both languages. Dijkstra et al. (1999) explained this interlingual homophonic effect as the

result of competition between the two phonological representations of homophones in the

target and the nontarget language. Indeed, although similar, the phonological realization of

interlingual homophones is never identical in the two languages. Inhibition is observed due to

competition between non-identical phonological representations activated by the target letter

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string. According to this explanation, competition between phonological forms may provoke

inhibition of the non-target language resulting in an increase in reaction time when

responding to interlingual homophones.

The inhibitory results in bilinguals replicate the homophonic effects observed in

monolinguals (Ferrand & Grainger, 2003; Pexman, Lupker, & Jared 2001), where French and

English native speakers responded more slowly to intralingual homophones compared to

control words. According to Pexman et al. (2001) this effect is due to feedback from

phonological representations to orthographic representations; the phonological representation

of a homophone activates two orthographic representations and engenders competition at the

orthographic level. Not all bilingual studies of interlingual homphones have reported

inhibition, however. Lemhofer and Dijkstra (2004) reported that bilingual participants

responded faster and more accurately to interlingual homophones compared to control words,

thus revealing facilitation rather than inhibition of interlingual homophones. This finding is

all the more intriguing as the authors used the same stimuli as Dijkstra et al. (1999).

Lemhofer and Dijkstra (2004) concluded from this variability across studies that further

investigation is required to clarify the role of phonological overlap in bilingual word

recognition.

Further experimental data with respect to the activation of phonological

representations in bilinguals were obtained by Haigh and Jared (2007). French-English

bilinguals performed an English lexical decision task to single words under monolingual

conditions, which is purported to be the most stringent test of interlingual activation

(Grosjean, 2001). The critical stimuli were interlingual homophones and their matched

English control words. It is important to note that the selected interlingual homophones were

low in frequency in English, the language of the list, but high in frequency in French--the

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bilinguals L1--to maximize the possibility of observing an interlingual homophone effect as

suggested by Pexman et al. (2001). Results showed that participants responded more quickly

and more accurately to interlingual homophones (Experiment 1) than they did to control

words. However, the addition of pseudohomophones to the stimulus list (Experiment 2),

which has been found to discourage the use of phonology and enhance the use of orthography

in making word/nonword decisions, annulled the effect for response times although the

interlingual homophone facilitation persisted in the error data. In general, these results replicat

those found by Lemhofer and Dijkstra (2004). Consequently, the findings were interpreted as

a facilitatory interlingual homophone effect in contrast to the inhibitory effect reported by

Dijkstra et al. (1999) and Doctor and Klein, (1992).

In light of these opposing results, Haigh and Jared (2007) pointed out that the absence

of a monolingual control group in the study reported by Doctor and Klein, (1992) precludes

determining whether the interlingual homophone effect they obtained was the result of

differences between control and experimental words or that of the specific processes

regarding interlingual homophones. In addition, the fact that the monolingual control group in

Dijkstra et al. (1999) made significantly more errors on the interlingual homophones than on

control words suggests that other factors may account for the differences observed between

the experimental and control stimuli. According to Haigh and Jared (2007), the stimuli used

by Dijkstra et al., (1999) and Lemhofer and Dijkstra (2004) did not produce a reliable

interlingual homophone effect given the high frequency of the homophones presented in their

studies. Indeed, Pexman et al. (2001) found that intralingual homophone effects are most

likely to be observed when presented homophones are low in frequency compared to their

high-frequency homophone mates. The orthographic patterns for high frequency counterparts,

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even though not actually presented, would be activated as much as the orthographic patterns

for low frequency words, resulting in competition at the lexical level.

Based on a distributed connectionist framework (Harm & Seidenberg, 2005;

Seidenberg & McClelland, 1989), Haigh and Jared (2007) accounted for the facilitatory

interlingual homophone effect as a result of the rapid activation of the phonological

representation of the English word given its phonological overlap with a high frequency word

in French, which was the native language of the bilingual participants. Competition between

English and French orthographic representations should not arise due to the small amount of

feedback from the phonological representations activated by the English word to the

orthographic representations of French words. In the case that phonological representations of

English words did activate orthographic representations of French words, little competition

should arise between orthographic representations of English and French words because of

their orthographic dissimilarity.

The Bilingual Interactive Activation model (BIA+) proposed by Dijkstra and van

Heuven (2002) is able to account for this facilitatory interlingual homophone effect as well, as

indeed underlined by Haigh and Jared (2007). The BIA+ model posits the existence of a

single phonological lexicon with two independent phonological nodes for words in each

language. In the case of French–English bilinguals, the English lexical phonological node

might be rapidly activated for an English interlingual homophone because of its association to

the French lexical phonological node, especially when the French mate is higher in frequency.

In contrast, English control words would need to await for sufficient activation of the English

lexical phonological node to be recognized, resulting in a delay for control words compared to

interlingual homophones. Yet another possibility to explain this facilitatory effect by the

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BIA+ model is the existence of excitatory connections between phonological representations

in each language.

Strong phonological effects in bilingual visual word recognition have also been

reported in a variety of priming paradigms (Brysbaert, et al., 1999; Duyck, 2005; Duyck,

Diependaele, Drieghe & Brybaert, 2004; Kim & Davis, 2003; Van Wijnendaele & Brysbaert,

2002). Some of these studies have argued that bilingual lexical access implies the pre-lexical

and automatic phonological coding of visually presented words, which has been demonstrated

in monolinguals (Berent & Perfetti, 1995; Grainger & Ferrand, 1996; Van Orden, 1987; for a

recent discussion of this debate, see Harm & Seidenberg, 2005). Most of the evidence

supporting this assumption comes from the masked phonological priming paradigm under

cross-lingual prime-target conditions. Using this paradigm, Brysbaert et al. (1999)

investigated whether the phonological and orthographic representations of both languages

were activated during bilingual visual word recognition. Results showed a homophonic effect

whereby Dutch-French bilinguals identified L2 target words (e.g. nez “nose”) faster following

L1 homophonic word primes (e.g. nee “no”) than following L1 graphemic control primes

(e.g. nek “neck”). Hence, bilinguals applied two different sets of grapheme-phoneme

correspondences, which suggests that both sets of correspondences are activated

simultaneously and interact with one another. This homophonic effect was also replicated

with nonword primes, which strongly argues for pre-lexical phonological coding. Other

studies have further evidenced automatic phonological coding of L1 words during L2 word

processing (Duyck et al., 2004; Kim & Davis, 2003).

Although all previous studies have shown evidence for the mediation of phonological

representations of both languages during L2 word recognition, a more consistent pattern of

data is needed to evaluate the role of phonological overlap across languages in bilingual

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lexical representation. Furthermore, it is important to note that all the results presented so far

in the literature involving interlingual homophones were obtained in tasks that required an

explicit behavioral response to the homophone. In the current study, the measure of interest is

event-related brain potentials (ERPs), which provide a continuous account of brain activity in

response to the presentation of a stimulus. In particular, we were interested in possible

modulations of the N400 response. From seminal work we know that modulation of the N400

amplitude is associated with the ease with which a word is integrated into a predetermined

context (Kutas and Hillard, 1980, 1984). The N400 is also sensitive to meaning integration

during single word processing (Holcomb, 1993). It is also hypothesized to index the ease of

accessing features of the long-term memory representation associated with a lexical item

(Kutas, Ferdemeire, 2000; Ferdemeire & Kutas, 1999). Under this assumption, any factor that

facilitates lexical access should reduce the N400 amplitude, as indeed attested by numerous

studies reported in the literature. Frequent and well known words are integrated faster and

produce smaller N400 amplitudes than less frequent words (Rugg, 1990; Van Petten & Kutas,

1990; see Lau, Phllips & Poeppel, 2008, for a recent discussion of the functional significance

of the N400 and the cortical areas underlying it). Last, in relation to other measures, the N400

has been found to be less sensitive to strategic or decision-related factors that frequently

influence reaction times (Holcomb, Grainger, O’Rourke, 2002; Kounios & Holcomb, 1992).

Of particular relevance for the current study is the observation that the N400

amplitude is directly proportional to the effort required to integrate the orthographic,

phonological and semantic knowledge relative to a word (Holcomb, 1993). Indeed, words

with large numbers of orthographic neighbors in both L1 and L2 have been found to generate

greater N400 amplitudes (Holcomb, et al., 2002; Midgley, Holcomb, van Heuven & Grainger,

2008). This increase in the N400 amplitude is hypothesized to occur because lexical stimuli

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activate not only their own representations but those of their orthographic neighbors as well,

resulting in an effort to inhibit the semantic information associated with these words. On the

other hand, reduced N400 amplitudes have been observed in response to cognates, that is

words with an almost complete cross-linguistic orthographic and semantic overlap (Midgley,

Holcomb & Grainger, in press). This reduced negativity has been interpreted as facilitation

due to a greater ease in mapping form onto meaning in single word recognition.

Herein we investigated whether bilinguals activate phonological representations from

both of their languages when reading silently in their L2. Stimulus materials were interlingual

homophones that had different spelling and meanings in English and French (e.g., pool/poule

which means ‘chicken’ in French) and were lower in frequency in English than their French

counterparts. Electrical brain activity was recorded while English monolinguals and French-

English bilinguals read these interlingual homophones in an entirely English language

context. Participants read a list of words for meaning and were asked to make decisions about

probes from a specific semantic category which encouraged them to process words at the

semantic level of representation (Bueno & Frenck-Mestre, 2008). Based on previous

behavioral data (Dijkstra et al., 1999; Doctor and Klein, 1992; Haigh and Jared, 2007;

Lemhofer and Dijkstra, 2004), we predicted a variation in the N400 amplitude in response to

interlingual homophones in comparison to control words (e.g. pool/pink), specifically for our

French-English bilingual participants. Any variation in the N400 amplitude for experimental

and control stimuli would suggest that both English and French phonological representations

were activated when reading in English. Consequently, English monolinguals should not

show any variation in the N400 amplitude with respect to the same stimuli. This type of

pattern will be interpreted as a confirmation of an interlingual homophone effect in bilinguals.

Moreover, the N400 amplitude differences should shed light on the controversy about the

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facilitatory or inhibitory effect of interlingual homophones. Larger N400 amplitudes should

be observed if an inhibitory effect takes place while processing interlingual homophones

compared to control words. In contrast, facilitation may reduce the N400 amplitude in

response to interlingual homophones compared to control words.

METHODS

Participants

Fourteen native English speakers (7 female) aged 18-22 years (mean age 19,1 years)

and 14 French L1 - English L2 speakers (3 female) aged 22-31 years (mean age 24 years)

participated in the experiment. All were undergraduate students at an American university and

received monetary compensation for their participation. Native English speakers reported

having no previous learning of or exposure to French. French L1 - English L2 late bilinguals

had learned English at school from the age of roughly 11 years and had, on average, 13 years

of experience with the English language. All were following a university curriculum in the

English language and were living in the United States at the time of participation. Their mean

self-rating of reading experience with the English language (on a scale from 1 to 7) was 5.8

(SD=.8). All participants reported to be right handed and had normal or corrected-to-normal

vision with no history of neurological insult or language disability.

Stimulus materials

Experimental stimuli included 48 English-French interlingual homophones and their

matched English control words. Interlingual homophones were monosyllabic English words

that were orthographically distinct from their homophonic French counterparts. English

homophones (e.g., pool) ranged in length from 3 to 5 letters (mean = 3.81) and in log

frequency from 0.48 to 3.29 (mean = 1.68 log frequency according to Wordgen data base,

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Duyck, Desmet, Verbeke, & Brysbaert, 2004). These English homophones tended to be lower

in written frequency than their French counterparts (e.g. poule) (t(94)= 1.87 p=.07) which

ranged in length from 2 to 6 letters (mean = 4.31) and in log frequency from 0.87 to 2.69

(mean = 1.98 log frequency according to Wordgen, 2004 data base). Control words were

monosyllabic English words (e.g. pink) that did not share the same phonology as the

interlingual homophones, but shared the same number of letters by using position-specific

coding, with the English homophones (e.g. pool) (mean, = 48% of orthographic overlap) and

with the French homophone counterparts (e.g. poule) (mean = 42% of orthographic overlap).

Orthographic overlap was calculated by using the application MatchCalculator, written by

Colin Davis. Control words were between three and five letters long (mean= 3.81) and

ranged in log frequency from 0.48 to 3.37 (mean = 1.67 log frequency according to Wordgen,

2004 data base). The mean number of neighbors for English homophones was 11.16

(range=1-23) and 11.12 (range=2-21) for control words. These means were not significantly

different (t(94)=0.06, p=.88). In addition, 144 filler words and 36 probes related to city and

country names were selected that matched the experimental words with respect to length and

frequency. For the resulting set of 276 items, each participant saw the same stimuli but in a

different random order of presentation.

Procedure

Participants were seated comfortably in a soundproof room. Words were displayed

visually one at the time on a computer screen in white uppercase letters on a black

background. Participants were asked to read the words for meaning and to perform a go/no-go

semantic categorization task in which they were instructed to press a button whenever they

saw a city or country name. Stimulus trials were presented for 500 ms followed by a 1000 ms

blank-screen (1500 ms inter-stimulus interval). After a set of 8 to 12 trials, a stimulus

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indicated that it was permissible to move or blink the eyes. This prompt remained on the

screen for 1500 ms followed by 500 ms of blank screen. Before the next trial appeared, a

fixation cross was presented for 1000 ms.

The experiment started with a short practice list to familiarize participants with the

experimental procedure. Oral and written instructions were given in English before the

practice trials and the experimenter did not speak French with the French-English bilinguals

to avoid activation of this language prior to the experiment. There were two pauses during the

experiment, the length of which was determined by the participants. The entire procedure

lasted approximately 40 minutes.

EEG recording

Electrophysiological data were recorded from 29 tin electrodes attached to an elastic

cap (Electro-cap International). Eye-related artifacts (vertical and horizontal eye movements)

were monitored using two additional electrodes, placed below the left eye and at the outer

canthus of the right eye. All electrodes were referenced to an electrode placed over the left

mastoid. The 32 channels of electrophysiological data were amplified using an SA

Instruments Bio-amplifier system with 6db cutoffs set at .01 and 40Hz. The output of the bio-

amplifier was continuously digitized at 200 Hz throughout the experiment. Epochs began 100

ms prior to stimulus onset and continued 1500 ms thereafter. Average ERPs were calculated

off-line from trials free of artifact (14% of critical trials were rejected overall, with no

difference between experimental conditions or participant groups).

Data Analyses

Mean ERP amplitudes were time-locked to target onset, preceded by a 100 ms pre-

stimulus baseline. The mean amplitudes for ERPs associated with homophones and control

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words were calculated per participant in a 400 – 600 ms time window to capture any typical

N400 effect. ANOVAS were performed on mean amplitudes with Group (native English

speakers vs. French L1– English L2 speakers) as a between participant factor and Target

(homophone vs. control) as a repeated measure.

Topographical analyses were based on the 29 channel electrode montage divided into

seven separate parasagittal columns along the antero-posterior axis of the head (see Fig. 1 for

the location of electrodes). The midline electrodes and those for the first lateral columns (C1)

on the left and right hemisphere were grouped for analysis with 3 levels of Electrode for each,

while the other two pairs of lateral columns (C2 and C3) were analyzed separately.

Hemisphere (left vs. right) was included as a factor in the two lateral analyses, with four or

five levels of Electrode.

Insert Figure 1 about here

RESULTS

Behavioral results

The analysis of behavioral data for semantic categorization task revealed a mean

percentage of accuracy of 90% (SD=2.94) for monolingual English speakers and 87%

(SD=3.14) for French-English speakers. Participants thus completed the task accurately,

which necessitated activating semantic memory. Recall, nonetheless, that participants

responded only to probe stimuli not to critical words, for which ERP data was recorded.

Electrophysiological results

Interlingual Homophone Effect

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Grand averages elicited by interlingual homophones and control words are plotted as

waveforms for a sample of electrodes in Figure 2 for monolingual English speakers and in

Figure 3 for French-English bilinguals. Visual inspection revealed a clear N400 response to

lexical items in both groups of participants. Plotted in Fig. 4 are the voltage maps resulting

from subtracting ERPs recorded to control words from ERPs recorded to interlingual

homophones. These plots reveal the spatial distribution of ERPs in response to critical words

for the monolingual and bilingual groups. Visual inspection revealed the presence of a

reduced N400 response, occurring around 400 ms and persisting until 600 ms, for

homophones in comparison to control targets at central and bilateral parietal sites for French-

English bilinguals but not for monolinguals.

Insert Figure 2, Figure 3 and Figure 4 about here

Statistical analyses revealed no reliable differences across conditions in the first 400

ms following critical word onset. Differences were observed, however, in the traditional N400

epoch as a function of critical words.

In the 400-600 time window, a trend for the effect of Homophone was observed at

central electrodes (F(1, 30)= 3.41, p=.07, MSe = 12.63) with no interaction as a function of

Site (midline and c1). An interaction between Homophone and Group was significant at

midline and c1 (F(1, 30)= 4.24, p=.05, MSe = 12.63) which was not modified by Site or

Electrode (F<1, for all sites). No further significant main effects or interactions were found at

either c2 or c3. To better characterize the effect of the Homophone, follow-up analyses were

carried out in each Group. These analyses revealed a main effect of Homophone for French-

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English bilinguals at midline and c1 (F(1, 15)=7.36, p<.01, MSe = 13.10), which was

modified by Site and Electrode (F(4, 60)=3.43, p<.01, MSe = .10) due to a larger effect at

midline (p<.001) than at c1 (p<.02). At lateral sites, the Homophone effect approached

significance only at c2, F(1, 15)= 3.47, p=.08, MSe = 3.47). In contrast, the monolingual

group showed no significant main effect of Homophone or interactions at any site (F<1, for

all sites).

In summary, these data suggest that interlingual homophones elicited an N400 effect

with a typical centro-parietal distribution for all participants. In the French-English bilingual

group specifically, the N400 effect was reduced for homophones in comparison to control

words, suggesting a privileged status for these words.

DISCUSSION

The present ERP study examined whether bilinguals activate phonological

representations of both of their languages when reading silently in their second language alone.

French-English bilinguals and English monolinguals read interlingual homophones and matched

control words while performing a semantic categorization task. Results showed different patterns

of ERPs elicited by the interlingual homophones for the two groups. Whereas monolinguals

presented no variation in N400 amplitude as a function of the type of word presented, bilinguals

showed a reduced N400 amplitude in response to interlingual homophones compared to control

words. The fact that modulation of the N400, as a function of word status, was limited to

bilinguals underlines the fact that this effect cannot be attributed to any properties of the stimulus

words in English apart from the phonological overlap with French words. Indeed, our results

clearly indicate that bilinguals’ cortical response to words in their second language was

influenced by the phonological overlap of these words in their first language. Moreover, this was

true even though the bilinguals read words exclusively in their L2. Overall, this finding provides

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further evidence that phonological representations of both languages are activated when

bilinguals read silently in their second language.

What, exactly, the reduction in N400 amplitude for homophones we observed for our

bilingual participants implies is yet an open question. The first hypothesis, which we indeed

support, is that the phonological overlap between the homophones, presented in the bilinguals’

second language (English), and the not-presented L1 (French) counterparts in fact facilitated

processing. Facilitation may occur when phonological representations of L2 interlingual

homophone members are matched to those of their L1 counterparts. In a recent ERP study on

bilingual lexical processing, Midgley, Holcomb and Grainger (in press) reported a reduced N400

effect to cognates. The authors concluded, in like manner to our current hypothesis, that the

reduced N400 effect reflects a processing advantage for words that share either orthography and

phonology or orthography and meaning across a bilingual’s two languages, as is the case for

cognates. This hypothesis is in line with the assumption that a reduced N400 response reflects

facilitated activation of features of long-term memory representations associated with the lexical

item (Ferdemeire & Kutas, 1999; Kutas & Ferdemeire, 2000). In this light, the processing benefit

we observed for interlingual homophones would be related to the overlap of phonologic features

stored in long-term memory for our bilingual participants. This facilitatory interlingual

homophone effect, revealed here by the bilinguals’ cortical response to these words, is

consistent with results obtained in two previous behavioral studies, which examined processing

via the lexical decision task (Haigh and Jared, 2007; Lemhofer and Dijkstra, 2004). Hence,

contrary to Dijkstra et al. (1999) and Doctor and Klein (1992), our findings underline the ease

with which bilinguals process interlingual homophones.

Nonetheless, a reduction in the N400 effect for homophones cannot be taken as

unequivocal evidence of facilitation due to the activation of multiple word meanings. In fact,

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based on the results from two recent monolingual ERP studies on the factors that affect lexical

access (Holcomb, Grainger & O’Rourke, 2002; Muller, Duñabeitia & Carreiras, 2010), one

could argue quite the opposite. In these studies, words with a greater number of orthographic

neighbors and/or semantic associates elicited increased N400 amplitudes in relation to words

with few neighbors and/or associates. These results were taken as evidence that the (at least

partial) activation of multiple lexical candidates produces an increase in the N400 response due

to increased lexical-semantic activation in the system. As such, it could be argued that the

reduced N400 amplitude we found for interlingual homophones is difficult to reconcile with the

activation of multiple meanings. Indeed, while our results clearly show that our bilingual

participants were sensitive to the presence of homophones, we cannot attest with certainty that

they fully activated multiple meanings for these words. Further work, currently in progress, is in

order to elucidate this question.

Furthermore, the present results offer evidence of nonselective activation of both

languages in a language specific context. Specifically, this was true at a phonological level, as

demonstrated by the interlingual homophone effect found in the present ERP study and that

reported previously in behavioral studies. In line with this assumption, the BIA+ model posits

that the visual presentation of a word leads to the parallel activation of semantic, orthographic

and phonological representations in both of the bilingual’s languages (Dijkstra & van Heuven,

2002). Thus, the facilitatory interlingual homophone effect may arise from the reciprocal

excitatory connections between the two phonological lexical nodes represented independently

for each member of an interlingual homophone pair. The native-language lexical phonological

node associated with an interlingual homophone might be easily activated, especially when the

L1 mate is a high frequency word, allowing for rapid recognition of the interlingual homophone.

With regard to control words, which have no phonological overlap with the L1, the L2 lexical

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phonological node would be activated more slowly without the prompt of the L1 homophone,

leading to a decrease in processing fluency for these words in comparison to interlingual

homophones. Haigh and Jared (2007) have furthermore suggested that these facilitatory

interlingual homophone effects should arise when the phonological representations of an L2

word overlaps with that of a known L1 word and little competition is present between the

orthographic representations in the two languages.

Note that the BIA+ model was inspired by connectionist models which postulate the

interactive activation of multiple codes in monolingual word recognition (e.g. McClelland &

Rumelhart, 1981 and Seidenberg & McClelland, 1989). These models posit that lexical

processing involves the interactive computation of orthographic, phonological and semantic

codes. Under this framework, each code (linked to orthography, phonology and semantics) is

represented by a set of units and each unit participates in the representation of many words; all

connections between units are used in processing all words. The processing benefit observed for

interlingual homophones can be explained in terms of increased activation of cross-linguistic

phonological units of these critical words. The cumulative exposure to similar phonological units

in bilingual lexical representations may have strengthened the connections across units, thus

leading to the enhanced processing of interlingual homophones. This is in line with one major

principle implemented in all connectionist models of language processing, which is that

frequency of exposure and learning determines connection strength across units (Seidenberg &

McClelland, 1989). Within this theoretical framework, the computation of interlingual

homophones would be facilitated given the strength of connections built up on the basis of

shared phonological units across a bilingual’s two languages.

While our data clearly show sensitivity to homophone status when our bilingual

participants were reading in their second language, we cannot make claims as concerns what

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might transpire when reading in the native language. Haigh and Jared (2007) indeed found that

parallel activation of homophones was restricted to second language processing. In other words,

bilinguals could not repress L1 phonological activation when reading in their L2, but the

opposite was indeed possible. Note, nonetheless, that in a masked priming paradigm, as opposed

to single word presentation, Duyck (2005) as well as Van Wijnendaele and Brysbaert (2002)

found that L2 homophonic primes facilitated L1 target processing, thus providing evidence in

favor of a strong language nonselective view on phonological coding in bilinguals.

An underlying fact in the present study is however, that highly fluent bilinguals still

showed parallel phonological activation of their two languages. Thus, on the basis of this

finding, one would predict greater cross-linguistic phonological activation for less proficient

bilinguals who would rely more on phonology when reading in their L2 as stated by Gollan,

Forster and Frost (1997) and Brysbaert et al. (1999) (but also see Duyck et al. 2004).

In conclusion, the results of this study suggest that bilinguals activate phonological

representations of both of their languages when they read silently in their second language. In

addition, the present study provides electrophysiological data that confirm the facilitatory

interlingual homophone effect observed in previous behavioral research (Haigh and Jared, 2007;

Lemhofer & Dijkstra, 2004). Our finding of parallel activation of phonological representations in

bilinguals provides further support to the theories of phonological mediation in visual word

recognition, which can be generalized to bilingual word processing. Finally, our results underline

the need for current and future models of bilingual word recognition to account for the role of

phonological representations during visual word processing.

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Figure captions:

Figure 1. Electrode montage and analysis sites.

Figure 2. Grand average wave forms for selected electrodes for English monolingual

particiapnts for interlingual homophones and control words.

Figure 3. Grand average wave forms for selected electrodes for French-English bilingual

particiapnts for interlingual homophones and control words.

Figure 4. Scalp voltage maps for interlingual homophones and control words for English

monolingual (top) and French-English bilingual (bottom) at three time points.

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Electrode montage and analysis sites.

553x607mm (96 x 96 DPI)

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Grand average wave forms for selected electrodes for English monolingual particiapnts for interlingual homophones and control words.

903x563mm (96 x 96 DPI)

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Grand average wave forms for selected electrodes for French-English bilingual particiapnts for interlingual homophones and control words.

927x656mm (96 x 96 DPI)

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Scalp voltage maps for interlingual homophones and control words for English monolingual (top) and French-English bilingual (bottom) at three time points.

378x334mm (96 x 96 DPI)

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