Effects of stimulus location and pattern upon the visually evoked cortical potential and the electroretinogram.

The pattern properties of the visually evoked potential and the electroretinogram have been investigated for phase alternated patterns of checks presented to the near periphery of the retina. When the eye was light-adapted, coarse patterns became relatively more effective for eliciting the evoked potential as the stimulus was moved away from the fovea. Fine patterns were most effective in the center of the field. The electroretinogram responded best to coarse spatial frequencies at all retinal locations. At a lower level of light adaptation the sensitivity of the evoked potential shifted to coarse spatial frequencies in the center of the field, but did not change appreciably in the periphery. The results may reflect some of the dynamic properties of visual fields.