Temporal spacing of pattern alternation and human visual response

The electroretinogram and the visual evoked potential were recorded in response to checkerboard stimuli presented in phase alternation. The times in which the pattern was in its two positions were changed within a fixed total cycle time of two seconds. Both the amplitude of the electroretinogram and the evoked potential were affected by the length of the time interval between alternations, but in opposite directions. An electroretinogram that closely followed a preceding response was reduced in size while an evoked potential was larger. The results indicate that there is an interaction between adjacent pattern areas at the retinal level.