Exposure duration affects the perceived direction of cyclopean Type II plaids

This study investigated the effect of exposure duration on the perceived di rection of cyclopean Type I and Type II plaids moving in the X/Y plane. The cyclopean plaids were created from grating components defined by binocular disparity embedded in a dynamic random-dot stereogram. The results showed that the cyclopean Type I plaid appeared to move in the intersection-of-con straints (IOC) direction across the range of exposures tested. However, the cyclopean Type II plaids appeared to move in a direction different from th e IOC with short exposures but near the IOC with long exposures. This perce ived directional shift was also obtained with luminance-defined Type II pla ids. A common pattern-motion mechanism that processes cyclopean and luminan ce motion signals appears responsible for the perceived directional shift o f the Type II plaids. (C) 2000 Elsevier Science Ltd. All rights reserved.