Lateralized effects of blurring: a test of the visual spatial frequency model of cerebral hemisphere asymmetry.

In a Physical Identity letter comparison task, blurring the stimuli impaired performance when stimuli were projected to the right visual field but not when stimuli were projected to the left visual field. Whether this effect was obtained for response accuracy or for reaction time of correct responses depended on whether the stimuli were difficult or easy to classify. In two experiments it is shown that when the classification task is so difficult that the error rates are high, the Stimulus Clarity x Visual Field interaction is restricted to response accuracy measures. When the classification task is so easy that the error rates are low in all conditions, the critical interaction is restricted to reaction time of correct responses. The results are consistent with the hypothesis that the left and right hemispheres are biased toward efficient processing of higher and lower ranges of visual spatial frequency, respectively.