Cerebral dominance and lateral differences in perception and memory

Abstract

The present investigation was designed to replicate a previous finding that tachistoscopically presented complex forms of low verbal association value would be more accurately recognized when presented to the left visual field than to the right, thus implying dominance of the right hemisphere for the perception of this type of stimulus material. The successful replication of this finding was important because of previous unsuccessful attempts to show such an effect. This finding, in conjunction with the well established right visual field (i.e. left hemisphere) superiority for the perception of verbal material, strongly supports the hypothesis that asymmetry in human perceptual performance reflects hemispheric asymmetry of function rather than peripheral factors. The second question investigated concerned the role of memory in producing perceptual asymmetry. Complex figures were presented for 15–25 msec in either the left or right visual field; after a delay of 0–20 sec, the subject was required to indicate whether or not a form presented in central vision was the target form. The results indicate that the observed left visual field superiority for these complex forms appears to arise from hemispheric differences in memory rather than from purely perceptual processes.