Bilingual memory revisited: An electrophysiological investigation of lexical and semantic representations in fluent bilinguals

The current study set out to investigate asymmetrical priming effects in fluent bilinguals in the context of bilingual memory models with event-related potentials (ERPs) and reaction time measures. Specific questions were whether more would become apparent about the underlying processes involved in within- and between language priming comparing the two techniques and if monolingual and bilingual language processing under the same processing conditions comparable.; Monolingual and bilingual speakers engaged in a paired lexical decision task (LDT, Experiment 1) and a sequential LDT (Experiment 2 & 3). Subjects in Experiment 1 were monolingual English and bilingual German/English speakers and monolingual English and bilingual Spanish/English speakers in Experiment 3. Stimuli were presented at three different stimulus onset asynchronies (0, 200, 800 SOA) in Experiment 1, and a 1025 SOA in Experiment 3.; Results in Experiment 1 revealed faster response latencies and higher accuracy in monolingual than bilingual speakers of English. While RT and ERP priming was comparable at the 200 and 800 SOA across groups, RT priming was small and ERP priming absent at the 0 SOA in the bilingual group, but large in the monolingual group.; RT and ERP measures displayed different word priming effects in Experiment 2 indicating that the activation of levels of representation might not vary as a function of word types. Monolingual English speakers showed associative RT priming but both associative and semantic ERP priming.; In Experiment 3 the overall response latency was faster and accuracy higher in monolingual English speakers than bilingual Spanish/English speakers. Within language comparisons revealed similar RT associative priming effects but less ERP priming across word types in English bilinguals than Spanish bilinguals. Between language comparisons found more associative priming in the Spanish/English than the English/Spanish condition, but more ERP priming across word types in the English/Spanish than the Spanish/English condition.; These results support a division of monolingual and bilingual language processing and a model of bilingual memory in which modality-specific fluency influences the speed of processing and the magnitude of the priming effect. The implications of these results for current models of bilingual memory and the current theory of the N400 component are discussed.