Laterality differences in sensitivity to line orientation as a function of adaptation duration

Since available evidence indicates that the two cerebral hemispheres are differentially sensitive to different types of stimulus information, and that they also utilize different strategies in processing information, is it possible that the two hemispheres are differentially sensitive to adaptation? Three groups of four subjects each were adapted to black and white gratings using three adapting durations: 500, 1,000, and 5,000 msec. Immediately following adaptation, a test grating was presented in either the left or right visual field. The task of the subject was to determine whether the lines of the adapting and test gratings had the same orientation or not. Analysis showed that in the 5,000-msec and 1,000-msec conditions, more errors occurred with left visual field presentations, responses to left visual field presentations took longer, and a bias-free measure showed that subjects were more sensitive to right visual field presentations. For the 500-msec group, there were no apparent differences between left and right visual fields presentations. The results indicate differential effects of adaptation on the two hemispheres, suggesting sensitivity differences between the two halves of the brain.