VISUAL PATTERN RECOGNITION IN THE CEREBRAL HEMISPHERES: THE ROLE OF SPATIAL FILTERING

The differences between the left and right cerebral hemispheres in terms of visual pattern recognition were examined in the context of the spatial filtering model of visual perception. On the basis of a wide range of evidence, it was hypothesized that the right hemisphere is superior in the processing of low spatial frequency and/or high contrast information, and that this superiority may underlie its predominant role in "gestalt" perception. The left hemisphere, on the other hand, was hypothesized to be more highly involved in an analysis of high frequency and/or low contrast information contained in the visual environment.;Analyses of variance revealed that discrimination performance (both in terms of latency and accuracy) was superior: (a) when low as compared to high frequency gratings were presented; (b) when the contrast of the gratings was in the moderate to high range; and (c) during the second of two experimental replications. In addition, discrimination performance proved superior overall in the right visual field (RVF). The magnitude of the RVF latency advantage was greater in the case of the high frequency gratings, as predicted, although this trend only approached significance. The results were discussed in relation to the predictions made by the spatial filtering model, as well as those of other theories of hemispheric specialization in visual pattern recognition.;The spatial filtering capabilities of the two hemispheres were assessed by presenting square-wave gratings to the left and right visual fields, which project almost exclusively to the primary visual cortical areas of the contralateral hemispheres. Twenty-four right-handed adult male subjects were required to discriminate two different orientations of each of six gratings varying in fundamental spatial frequency and level of contrast.