Physiological responses to verbally inaccessible pictorial information in the left and right hemispheres. Neuropsychology

Abstract

We investigated the effects of very brief pictorial information on transfer between the cerebral hemispheres through recordings of skin conductance responses. The pictorial stimuli had been judged previously as "neutral", "positive", or "negative" by an independent group of subjects. The verbally-available stimuli (VA) were neutral whereas the very brief, verbally-unavailable stimuli (VU) were positive or negative. The VA and VU stimuli were presented simultaneously, either in the same visual half-field (intra-hemispheric interference) or in the opposite visual half-field (inter-hemispheric interference). In a third condition, there were only VA stimuli in either visual field (no interference). We found that the right hemisphere was especially sensitive to negative VU presentations, both in the inter-and intra-hemispheric interference groups. The left hemisphere showed a corresponding sensitivity to positive interference, but only in the inter-hemispheric interference group. These findings confirm the hemispheric roles in mediating positive versus negative emotions and they show that in the interplay between hemispheric specialization and commissural transfer, left to right transfer can take place without linguistic cognition.