The influence of language on exact additions in bilingual adults.

To which degree is language involved in arithmetic? We investigated this question in a German-French bilingual setting. In Luxembourg, bilingualism is acquired through education: mathematics are taught in German in primary and in French in secondary school. Interestingly, the decades and units within two-digit number names follow the unit-decade order in German but the decade-unit order in French. Forty-eight bilingual adults performed simple and complex additions. Participants had to orally respond either in German or in French. Additions were presented in different conditions: (1) visual Arabic presentation, (2) auditory presentation (in German or in French), and (3) as a dual task in which visually presented additions were preceded by visually presented semantic judgments to indirectly activate a German or French language context. The results showed that participants performed complex calculations better in the dominant language (German), while there were no differences for simple calculations. Thus, language proficiency seems to be crucial for the computation of more complex calculations, whereas arithmetic facts can be retrieved equally well in both languages. Further, adding language at the input level (auditory presentation) enhanced performances for simple calculations, especially in the non-dominant language (French), while it was exactly the opposite effect for complex calculations. Additionally, visual additions were better performed within a surrounding linguistic context (3) than alone (1) in their non-dominant language, suggesting the crucial role of the linguistic context of an addition task in bilinguals. Taken together, these results support the view of a strong language impact on calculations.