Reversal of asymmetry in human perceptual performance as a function of labeling, mode of response, and familiarity.

It has previously been demonstrated that certain characteristics of the stimulus, specifically visual complexity and verbal association value, as well as mnemonic factors are important in producing the usually obtained asymmetry in human perceptual performance, and thus presumably, hemispheric asymmetry of function. The present research demonstrated that the usual superiority of the left visual field for high-complexity, low-association-value visual forms can be reversed by the acquisition and use of verbal labels for such stimuli but is only attenuated when the labels are not used to respond to the stimuli. Simple familiarity with the visual stimuli attenuated the difference between the fields, but here there was no reversal. Implications of these results for hemispheric processing are discussed.