Baseline asymmetries in brain electrical activity predict dichotic listening performance.

Forty-four right-handed participants were assessed on 2 occasions 6weeks apart on electrophysi-ological measures of activation asymmetry derived from spectral estimates of electroencephalo-gram (EEG) alpha power in homologous scalp electrodes. Approximately 4 months following the final EEG assessment, participants were administered a dichotic listening CV-syllables task. Overall, participants exhibited a highly significant right-ear advantage. Differences among individuals in ear asymmetry were predicted by the earlier ecorded electrophysiological d ta. Participants with greater activation in left-sided posterior temporal and parietal regions howed a larger ight-ear advantage. In addition, a larger ight-ear advantage was predicted by right-sided prefrontal activation. These data indicate that some of the variance in dichotic listening performance can be explained by dispositional ctivation asymmetries and is associated with a complex pattern of posterior and anterior activation asymmetries. A number of investigators of brain asymmetry have distin-guished between hemispheric specialization and hemispheric activation (e.g., Davidson, 1988; Levy, 1983). Hemispheric specialization refers to differences between the two cerebral