How do bilinguals handle interhemispheric integration? Evidence from a cross-language study

The focus on interhemispheric interaction and integration has become a prominent aspect of laterality research. The aim of the present behavioral study was to determine whether hemisphere advantage differs between language groups. This was done by comparing how hemisphere advantage affects interhemispheric integration in monolingual and in bilingual individuals. Sixty university students (20 English monolinguals, 20 Hebrew bilinguals, and 20 balanced Arabic bilinguals) participated in two experiments, in which a lexical decision task was performed in the left and/or right visual field. Stimuli were presented unilaterally and bilaterally, whereby participants were cued to respond to the stimuli. In Experiment 1, all three groups showed an effect of lexicality, that is, participants responded to word stimuli faster than to non-word stimuli, with the Hebrew and Arabic groups showing a word advantage in spotting errors. In addition, all groups except the Hebrew group showed the expected right visual field advantage in accuracy, and the English group demonstrated this advantage in reaction time as well. In Experiment 2, responses to non-word stimuli were equally accurate in the left and right visual fields, but reaction time were faster for stimuli presented in the left visual field. The performance of balanced bilingual Arabic and unbalanced bilingual Hebrew reading groups was significantly better in the bilateral condition than in the unilateral condition. The results supported the notion that bilingual individuals show more effective interhemispheric communication and that they enjoy relative superiority in their interhemispheric processing in response to task demands.