The search for a bilingual advantage in executive functionsa developmental perspective.

Résumé

Bilinguals need very intensive language-control mechanisms to produce effective communication and avoid intrusions from the non-target language, because both languages are always active in a bilingual mind (Thierry & Wu, 2007), competing with each other. It is mostly assumed that bilinguals apply inhibition to the non-target language (see, for example, the IC model, Green, 1998). This constant need of inhibition makes bilinguals much better at their general inhibitory abilities as compared to their monolingual counterparts, as claimed by the bilingual advantage defenders (Bialystok et al., 2005). However, recent findings suggest that the repeatedly shown bilingual advantage effect in tasks tapping into domain general inhibition might stem from uncontrolled factors associated to bilingualism, rather than from bilingualism itself, as well as to small sample sizes (Paap & Greenberg, 2013). Crucially, previous evidence tended to neglect the importance of factors such as immigrant status or socio economic status. In the present thesis I aimed at testing the reliability of the criticisms to the bilingual advantage by testing large samples of carefully matched bilingual and monolingual children, young adults and seniors in sets of classic tasks that tap into domain general executive functions, such as Stroop, Flanker and Simon tasks. I found no indication of the bilingual advantage whatsoever, since every bilingual and monolingual group behaved comparably in every task, obtaining highly similar indices. The results are discussed and interpreted in the light of different perspectives.