An ERP Study On The Influence Of Chinese-english Bilinguals' L2 Proficiency On Their L1 And L2 Mental Lexicon Representational Structure

As a research focus in the psycholinguistics, studies on bilingual mental lexicon representation have attracted many researchers' attention in the past few decades, and have developed a range of theoretical models that have allowed researchers to begin to tap some of the major long-standing questions of the field. Although there are many inconsistencies in research results due to divergent research methods and subjects on bilingual mental lexicon, including the common-storage and separate-storage dichotomy, word association model and concept mediation model opposition, and language selective versus nonselective access dichotomy and so on, it is yet important to delve into the possible factors that may influence bilingual mental lexicon processing such as L2 proficiency.The present study attempts to explore how L2 proficiency influences bilingual semantic processing, in the hope that it may generate some evidence from Chinese-English bilinguals for what RHM has predicted about L1 and L2 semantic processing by the ERPs analysis. The following research questions are addressed: (1) Does the difference of processing mechanism in word recognition between L1 and L2 of less proficient Chinese-English bilinguals is greater than that of proficient bilinguals according to ERPs data (anterior negativity and posterior N400 during 300-500ms)? (2) Do Chinese-English bilinguals exhibit attenuated posterior N400 amplitude and delayed anterior negativity in English word recognition compared with native speakers of English? (3) If they do, how does that differentiation reflect the bilingual lexical representation and processing mechanism?The subjects were 15 non-English major postgraduate students and 15 English major postgraduate students and 9 native speakers of English from Chongqing University. According to the subjects'English proficiency level, they were divided into less proficient Chinese-English bilingual group (non-English major) and proficient Chinese-English bilingual group (English major) and native speakers group. In three experiments, participants were instructed to monitor a stream of words for occasional probes from one semantic category, and rapidly press a single button whenever they detect a probe item and ERPs were recorded to non-probe critical items. It intends to study the amplitude and peak latency of ERP N400 component in this go/no-go semantic categorization task. All the ERP waveforms were collected by Stim2 program were off-line analyzed by Scan 4.3 of Neuroscan software and data by SPSS 17.0. The results showed that the processing of L1 and L2 in late Chinese-English bilinguals of different proficiency levels exhibit similar characteristics as reflected in the ERP waveforms elicited by their L2 compared to L1, and that these bilinguals'(even the proficient bilinguals') processing their L2 (English) words still shows great distinction as compared with English native speakers'processing their mother language.The findings are partially in support of RHM assumptions. The limitations of the current study and implications for future research are also discussed.