Abstract

Adaptation paradigms have proved extremely useful for revealing the tuning characteristics of visual mechanisms. As part of our research into stereopsis, we have used adaptation to study the disparity tuning of mechanisms which detect interocular correlation. Using a temporal 2AFC paradigm and the method of constant stimuli, we measured interocular correlation thresholds for dynamic random-dot surfaces over a range of disparities both before and after adaptation to a 1.0 correlated surface at some fixed disparity. In the adaptation sessions, subjects viewed 1.0 correlated surfaces for a duration of 1 min before each session and for 0.5 s before each interval of each trial during the session. Threshold elevation was defined as the ratio of post- to preadaptation threshold for a given disparity, and the threshold elevation vs disparity function revealed the tuning profiles of the mechanisms centered on or near the adapting disparity. Tuned mechanisms were observed both on and away from the horopter. The full width of the tuning functions varied with the adapting disparity, from ~5 min of arc at the horopter to more than 25 min of arc for adaption at 20 min of arc. Some facilitation was observed at disparities distant from the adaptation disparity, suggesting inhibitory flanks.

© 1989 Optical Society of America