Cognitive and Affective Response As A Function of Relative Hemispheric Involvement

Abstract

We sought to determine the cognitive and affective reaction to a communicative stimulus as a function of relative hemispheric involvement, and to examine by inference the internal composition of these processes. Right-handed men were asked to evaluate the sound quality of a taped radio broadcast. Each subject (n = 10) subsequently heard either a personally relevant or irrelevant advocacy that was either proattitudinal or counter-attitudinal. An additional ten right-handed men heard a neutral and obscure news story and constituted an external control group. After listening to the tape, subjects rated their agreement with the advocacy and listed their thoughts. EEG activity was recorded from the left (P3) and right (P4) parietal lobes, was integrated through an 8–13 Hz band-pass filter, and transformed to yield a ratio score of the differences between alpha activity in the right and left hemispheres over the sum of the alpha activity in the right and left hemispheres (P4 − P3)/(P4 + P3). Subjects then were classified as having displayed either relative major or minor hemispheric involvement on the basis of a median split of the ratio-scores. Analyses revealed that persons who displayed relative major hemispheric involvement tended to agree more with the pro- and less with the counterattitudinal advocacy when the issue was highly rather than slightly relevant. Persons who displayed relative minor hemispheric involvement, however, tended to counterargue and disagree with both pro- and counterattitudinal advocacies when the issue was highly rather than slightly relevant. Finally, there were no differences between the ratings of the neutral advocacy by persons who displayed major and minor hemispheric involvement. Two interpretations of these data which assume higher mental processes to be localized functions were considered and rejected. It is concluded that Luria's (1973) concept of functional systems provides the most parsimonious interpretation, and the nature of the functional system possibly underlying the present results was considered.