Brain potentials reveal semantic priming in both the 'active' and the 'non-attended' language of early bilinguals

A key question in the study of bilingual functioning is whether both the languages known are active at all times or whether one language can be selectively inactivated when bilingual individuals are tuned to the other language. Psycholinguistic and neuroscientific investigations have provided inconsistent data regarding the level of semantic activation of the two languages, even in the case of highly proficient bilinguals. In the present study, highly proficient, early Welsh/English bilinguals were presented with words in both their languages and were required to make word length decisions on words in one language while disregarding words in the other. Participants were not explicitly told about the organization of the word stream in pairs manipulating (a) semantic relatedness, (b) language of the prime and (c) language of the target in a fully counterbalanced two-by-two-by-two design. We observed significant semantic priming for both English and Welsh target words, irrespective of the active language, and independent of performance in the low-level letter counting task. We conclude that accessing the meaning of a written word is automatic in the two languages even when fluent bilingual adults are instructed to disregard words in one of their languages.