HEMISPHERIC-SPECIALIZATION FOR EMOTIONAL EXPRESSION

It has been hypothesized that the left hemisphere is specialized for p ositive, and the right for negative, emotional expression. If this hyp othesis is correct, the affected hemisphere should be inactive while t he opposite, intact hemisphere mediates the abnormal emotional reactio n. To help determine if such hemispheric emotional specialization exis ts, we reviewed videotapes of emotional reactions following unilateral intracarotid amobarbital injections and measured the interval from dr ug effect to emotional expression. Mean emotional response onset time was 30.2 seconds for positive (laughter) reactions, which were most fr equent after right hemispheric anesthesia. Mean onset time was 6.0 sec onds for negative (crying) reactions which occurred only after barbitu rization of the left hemisphere. Since these onset times are shorter t han the period of hemispheric inactivation, results support the hypoth esis of left hemisphere specialization for positive, and the right for negative, emotional expression.