The effect of language and mode on two-digit magnitude judgments in German-French bilingual adults

The study examined the effect of language and presentation mode on numerical processing skills in German-French bilinguals. This bilingual combination is particularly interesting because the order of two digit number words is inversed in both languages: decade-unit in French but unit-decade in German. Further, previous studies used written number word presentations as verbal notation to activate language, which are, however, rarely used in everyday life. The present study therefore tackled the question whether two-digit magnitude judgments are affected by the presentation mode (visual Arabic vs. auditory words) and the language (German vs. French)? Data stem from proficient German-French bilinguals (mean age: 25,3 years. The within-subject design involved two-digit number pair comparisons presented visually and auditory in German and in French. In line with previous studies, participants responded faster and more accurately on compatible than on incompatible trials in the visual Arabic presentation mode in both languages (compatibility effect): In compatible number pairs, the decades and units concord to the same magnitude decision (e.g. 23_57; decade: 2<5 and unit:3<7) whereas decade and units discord (47_82; decade: 4<8 but 7>2) for incompatible number pairs. In the auditory mode, the results showed a tendency for a regular compatibility effect in German and an inverse compatibility effect in French with participants responding faster on incompatible trials suggesting that bilinguals process numerical tasks in the language of presentation similar to monolinguals using the same language. Conclusively, the results imply differential numerical processing according to the presentation mode (visual Arabic vs. auditory words) and the language (German vs. French).