First language lexical activation during second language sentence comprehension in highly proficient bilinguals

Abstract

One of the most intriguing aspects of cognition is the way the bilingual brain deals with two languages. In this sense, a central question is whether knowledge of one language interferes in the processing of the other in everyday language use. The present thesis studied cross-language lexical interaction in highly proficient Spanish-English bilinguals who learnt English as a second language after age 10. A semantic incongruity task was used in which bilinguals read English sentences whose final words were either congruent or incongruent with the rest of the sentence context. While participants performed the task, their neural activity was recorded using electroencephalography (EEG). Event-related potentials (ERPs) were extracted and the semantic incongruity marker, N400, was used to assess electrical brain activity. Critical stimuli were English words whose Spanish translation equivalents shared an initial segment of their phonological representations with those of the most expected words for each sentence. For example, in the sentence “My brother swept the floor with a...”, 'broom' is an expected and congruent final word, while 'foam' is an incongruent ending. However, the Spanish translation equivalents of these words, 'escoba' and 'espuma', respectively, start with the same syllable. Participants showed no differences in N400 amplitudes for incongruent words with this sound repetition compared with incongruent endings without it (e.g. broom-foam; escoba-espuma vs. broom-dessert; escoba-postre). However, significant differences were found in N400 peak latencies, in which incongruent words that had this initial sound repetition peaked significantly later than incongruent words without phonological overlap. These results suggest a co-activation of English and Spanish words during second language word comprehension in sentence reading, supporting and extending the view that bilingual word processing is non-selective.