[Depth perception and amplitude of VEPs for variations of dot density in static random dot stereograms]

Relative changes in depth perception and amplitude of VEPs were compared when the dot density in static random dot stereograms was altered. The maximum amplitudes of negative potentials evoked by either stereogram or uncorrelogram were recorded from the occipital region of human scalp. The peak latency was in the range of 160 to 260 msec, averaging 197 msec in 18 subjects. The amplitude of negative potentials evoked by either stereogram or uncorrelogram was always larger than that evoked by correlogram. The amplitudes on either stereograms, uncorrelograms or correlograms did not significantly increase when the dot density was increased, and there was no significant difference in amplitude on either stereogram or uncorrelogram. Depth perception did not closely correlate with the dot density nor with the amplitude of negative potentials. These results suggest that the amplitude of negative potentials may represent activities of disparity-sensitive neurons elicited in a trigger feature manner, but it does not reflect activities of the higher order process of depth perception.