Abstract
Previously, we found that a motion aftereffect (MAE) in depth can occur after adaptation to motion-in-depth in random-element stereograms (VSS 2005). In the present study, we investigated the depth selectivity of the MAE in depth. The adaptation stimulus consisted of two frontoparallel surfaces, one above and one below the fixation point. These surfaces were depicted by random-dot stereograms that were temporally correlated (RDS) or uncorrelated (DRDS). During the 2-min adaptation phase, the disparity of one surface increased and that of the other surface decreased linearly and repeatedly to simulate smooth motion-in-depth. The range of these disparity ramps was −26.2 to −8.72, −8.72 to +8.72, or +8.72 to +26.2 arcmin, where positive and negative values indicate crossed and uncrossed disparity. The test stimulus consisted of two stationary frontoparallel surfaces depicted by a RDS with a fixed pedestal disparity of either −17.4, 0, or +17.4 arcmin. Under RDS adaptation conditions, robust MAE in depth occurred. The duration of this MAE in depth did not depend on the relation between the disparity range of the adaptation stimulus and the pedestal disparity of the test stimulus. Under DRDS adaptation conditions, MAE in depth did not occur. These results suggest that the adaptable processes used to detect motion-in-depth from binocular cues are insensitive to pedestal disparity.
The support of Province of Ontarion (Premier's Research Excellence Award) and NSERC (Canada) are greatly appreciated.