SIMULTANEOUS VERBAL AND AFFECTIVE LATERALITY EFFECTS

By analyzing the error scores of normal participants asked to identify a specific word spoken in a specific tone of voice (for example, the word ''tower'' spoken in a happy tone of voice), we have been able to demonstrate concurrent verbal and affective cerebral laterality effect s in a dichotic listening task. The targets comprised the 16 possible combinations of four two-syllable words spoken in four different tones of voice. There were 128 participants equally divided between left- a nd right-handers, with equal numbers of each sex within each handednes s group. Each participant responded to 144 trials on the dichotic task , and filled in the 32-item Waterloo Handedness Questionnaire. Analysi s of false positive responses on the dichotic task (responding ''yes'' when only the verbal or only the affective component of the target wa s present, or when both components were present but were at opposite e ars) indicated that significantly more errors were made when the verba l aspect of the target appeared at the right ear (left hemisphere) and the emotional aspect was at the left ear (right hemisphere) than when the reverse was the case. A single task has generated both effects, s o that differences in participants' strategies or the way in which att ention is biased cannot account for the results. While the majority of participants showed a right-ear advantage for verbal material and a l eft-ear advantage for nonverbal material, these two effects were not c orrelated, suggesting that independent mechanisms probably underly the establishment of verbal and affective processing. We found no signifi cant sex or handedness effects, though left-handers were much more var iable than were right-handers. There were no significant correlations between degree of handedness as measured on the handedness questionnai re and extent of lateralization of verbal or affective processing on t he dichotic task. We believe that this general technique may be able t o provide information as to the nature and extent of interhemispheric integration of information, and is easily adaptable to other modalitie s, thus holds great promise for future research.