Morphological and orthographic effects on hemispheric

Abstract

We tested the effects of morphological and orthographic differences between English, Hebrew, and Arabic on the functioning of the two cerebral hemispheres. University students who were native speakers of each of the three languages performed a lateralized consonant-vowel-consonant (CVC) identification task. The stimuli were presented vertically in three conditions: left visual field (LVF), right visual field (RVF), and bilaterally (BVF). Three dependent measures were used: (1) exposure duration of the stimuli in order to achieve a 50% error rate, (2) total number of errors in each presentation condition and (3) the difference between errors on the first letter and errors on the last letter, a qualitative measure of sequential processing. Arabic readers required longer exposure durations of the syllables in order to achieve a 50% error rate than Hebrew readers, who in turn, required longer exposure durations than native English readers. Readers of all three languages evinced left hemisphere specialization for this linguistic task and a bilateral advantage. The qualitative patterns revealed that the Arabic and Hebrew speakers showed the same hemispheric difference pattern, that was different from the one shown by English readers, and that Arabic readers showed a qualitative pattern suggesting higher levels of sequential processes in both hemisphere than readers of Hebrew and English. We interpret this as reflecting the adaptation of hemispheric abilities to reading languages that differ in morphological structure and orthography.