Number processing of Arabic and Hebrew bilinguals: Evidence supporting the distance effect

In the current study, a direct assessment of the effect of language lexical-syntactic structure and magnitude semantic access on numerical processing was made by contrasting the performance of Arabic/Hebrew bilinguals in a digital (Hindi-digits/Arabic-digits) and verbal numerical comparison task (Arabic, an inverted language: Units-Decades, Hebrew, a non-inverted language: Decades-Units). Our data revealed in the digital presentation format (Experiment 1) a regular distance effect in Arabic language-Hindi digits and Hebrew language-Arabic digits, characterized by an inverse relation between reaction times and numerical distance with no difference in the mean reaction times of participants in Arabic-L1 and Hebrew-L2. This indicates that both lexical digits of two-digit numbers in L1 and L2 are similarly processed and semantically accessed. However in the verbal presentation format (Experiment 2) a similar pattern of distance effect was found, but the mean reaction times in Arabic were lower than in Hebrew in each numerical distance. This indicates that the processing of two-digit number words in L1 and L2 is semantically accessed and determined by the syntactic structure of each language.