Dual-task performance in late proficient bilinguals.

A dual task, consisting of speeded tapping during concurrent silent and aloud reading, was employed to investigate hemispheric specialisation for both first (L1) and second (L2) language in late proficient bilinguals living in the L2 environment. Overall, bilinguals and matched monolinguals showed more right- than left-hand interference during concurrent tasks, indicating left lateralised speech, and more interference while reading aloud than while reading silently. Importantly, however, bilinguals showed more left-hand interference compared to monolinguals during both L1 and L2, suggesting that the right hemisphere may participate to a greater extent during language tasks in bilinguals relative to monolinguals. The data indicate more bilateral hemispheric involvement for both L2 and L1 in late proficient bilinguals living in the L2 environment.