Failures to confirm the spatial-frequency hypothesis: Fatal blow or healthy complication?

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Abstract
This paper examines the validity of the hypothesis that the two cerebral hemispheres are differentially sensitive to the outputs of the spatial-frequency channels. Recent empirical evidence bearing on this hypothesis is reviewed first, along with a discussion of some methodological problems inherent in its evaluation. An experiment is then reported in which indirect and direct means of testing the spatial-frequency hypothesis were combined. In a face-categorization task, three versions (broad-pass, low-pass, and coarsely quantized) of 16 faces were laterally presented at either 40 or 180 msec, in a within-subjects design. The three face versions were processed significantly faster after left than right visual-field presentation at 40-msec exposure, but a different pattern of visual-field asymmetry prevailed for each version at 180-msec exposure. While most of the findings were consistent with the view that the two hemispheres are biased toward efficient processing of different spatial-frequency contents, no visual-field asymmetry was obtained for low-pass faces, in contradiction with the predictions of the hypothesis. Additional analyses indicated that exposure duration, spatial frequency, and practice effects intricately interacted in determining the patterns of visual-field asymmetries. Implications of these results for the spatial-frequency hypothesis are discussed.