The Binocular Ver

Abstract

Although the visual evoked response (VER) is frequently used to assess binocularity, the contribution of the monocular components to the binocular VER is poorly understood. In a typical binocular situation, both eyes view the same stimulus pattern and the amplitude of the binocular VER is approximately 1.4 times larger than the amplitude of either monocular response. This parallels psychophysical reports of binocular brightness and contrast summation. We have examined checkerboard (14’ checks) pattern-reversal (3.75 Hz) VERs evoked from observers with normal binocularity using conditions in which interocular luminance differences (from 0.0 to 2.0 log units) were established. We found that for luminance differences up to 0.6 log units, the amplitude of the binocular VER did not vary significantly. Larger luminance differences resulted in decreased amplitudes with luminance differences between 1.3 and 2.0 log units resulting in amplitudes significantly smaller than the amplitude of either monocular VER. These results imply some type of inhibitory binocular interaction. Furthermore, observers with anomalous binocularity exhibited deviations from this normal pattern.