Hemispheric asymmetry (lateralization) in electroencephalographic activity while viewing familiar and unfamiliar patterns from Kimura figures.

Kimura Recurring Figures were presented after the priming trial to the upper or lower, left or right, tachistoscopic fields while monopolar electroencephalographic activity was measured over the left and right parietal, occipital, and temporal lobes for 9 men and 9 women. The relative proportions of alpha rhythms during the 2 sec after each of 64 presentations were employed as the primary measure. The powerful asymmetry in electroencephalographic activity, manifested as a paucity of alpha activity over the right temporal lobe compared to the left temporal lobe, was not observed for the parietal or occipital regions. There was conspicuously more relative activity over the parietal and occipital lobes, but not over the temporal lobes, during presentations of the familiar figures compared to the unfamiliar figures. Several interactions--explaining more than 25% of the variance--between gender, left and right hemispheric EEG activity, and visual quadrants were consistent with lateralization of function and gender differences in functional brain organization.