Hemisphere asymmetry in the detection of gratings of varying spatial frequency

Visual field symmetry in contrast sensitivity was investigated under conditions of spatial uncertainty. The stimuli were sinusoidal gratings of varying spatial frequency (SF). They were presented randomly in the left, right or in both visual hemifields. The percent detected gratings were slightly higher than the gratings in the left visual field except for gratings of low SF (0.24-0.48 c/deg). The results suggest the existence of a slight left-field (right-hemisphere) superiority in detecting stimuli of medium and high SF. The asymmetry is too slight to allow any significant difference in the SF-content of the neural representation of the left and right halves of the images; neither might it provide an explanation of some recent data on hemispheric specialization, in particular visual tasks.