The effect of inter-ocular delay and repetition interval on depth perception

Abstract

Observers viewed a continuously illuminated, binocular standard stimulus, adjacent to which appeared a briefly illuminated, binocular comparison stimulus. Using the method of adjustment, observers positioned the comparison stimulus in depth so that it appeared equidistant to the standard stimulus under conditions in which an interocular delay in stimulation occurred with respect to the comparison stimulus. It was found that: (1) little change in equidistance settings occurred with delays of 32 msec or less, but that with larger delays the apparent position of the comparison stimulus shifted away from the observer. (2) Increasing the time interval between successive pairs of comparison stimulus presentations from 150 to 300 msec resulted in a similar shift in apparent position. (3) There was an interaction between delay and repetition interval such that the repetition interval had a larger effect on equidistance settings for longer delays. The results were interpreted as supporting the notion of a continuum between stereoscopic-binocular and monocular stimulation. Physical simultaneity was not a necessary condition for stereopsis.