ABSTRACT
The spatial-frequency hypothesis derives from two sources. One is research on the influence of input factors on hemispheric differences in visual information processing. The other source is based on both psychophysical and electrophysiological research that indicates that the visual system may analyze a visual stimulus in terms of its spatial-frequency Fourier components. According to the spatial-frequency hypothesis, the direction of hemispheric asymmetries will be jointly determined by the spatial-frequency information contained in the visual stimulus, that is, information available for higher level processing, and the information required for a specific task. Hemispheric interaction between two gratings of the same spatial frequency can be obtained when both are of low spatial frequency, close to the vertical midline, and flickered at a low temporal frequency. The findings of inhibition and facilitation in the hemispheric transfer of low-spatial-frequency information in early visual processing may have important implications for studies that use bilateral stimulus presentations.
