Neuroelectric measures of lateral specialization in relation to performance.

Four experiments were undertaken to study EEG asymmetry in relation to cognitive specialization of the hemispheres of the human brain and in relation to the proficiency of behavioral performance. Individual differences in the functional significance of alpha lateralization were noted, but there were, within subjects, consistent indications of lateral specialization and of the influence of alpha asymmetry on reaction time. Simultaneous demands for both input processing and motor output control by a given hemisphere caused a decrement in reaction time performance. The decrement appeared to involve impaired perceptual processing, as indicated by factor analysis of the evoked potential. A factor identified as P300 was least represented in the wave forms associated with conditions leading to long reaction times.