Lateralized differences associated with semantically varied auditory material

EEGs were recorded from 13 subjects while they listened to four tape-recorded passages differing in semantic content. The distribution of alpha band power over the two hemispheres, measured at T3/T4, was found to show significant task-dependent shifts. More reality-oriented passages tended to be processed with greater left-hemisphere involvement, while "pleasurable" material showed significant right-hemisphere involvement. Since the differences in laterality were not related to grammatical measures of linguistic complexity, the apparent shifts were attributed to semantic differences between the tasks. Explanation of the results is made in terms of a theory of the metacontrol of cerebral processing.