Abstract
[Purpose] Motion in depth can be perceived based on interocular velocity differences (IOVDs) caused by monocular motion aftereffect (MAE). In order to investigate how the IOVD integrates signals from the luminance and color motion channels, we conducted experiments to reveal whether this integration is implemented before or after the comparison of the velocity signals from the two eyes. [Experiment] We measured cross adaptation effects between luminance and color motion signals in MAE of motion in depth (3D MAE). Adaptation stimulus was either luminance or red/green gratings drifting laterally in Exp. 1 and we also used yellow/blue gratings in Exp. 2. After adapting either the left or right eye to the drifting grating, the duration of 3D-MAE was measured with the static version of the color or the luminance grating. To confirm color motion system is concerned in color motion conditions, we varied temporal frequency (with a fixed spatial frequency), expecting different temporal frequency characteristics between the luminance and color motion systems. [Results] After the color adaptation, MAE duration showed longer with lower temporal frequencies (lowpass) while it showed the longest around 5 Hz after the luminance adaptation (bandpass) for both 2D- and 3D-MAEs with longer absolute duration for 2D-MAE. This trend was the same for the luminance and color tests both in Exps. 1 and 2. These results indicate 1) that color motion signals are used to see motion in depth through the IOVD and 2) that integration of color and luminance motion signals occurs at a stage of 2D motion and the IOVD is calculated from the combined motion signals. The preset results also suggest that there is an energy based color motion system since it is highly unlikely to calculate IOVDs through a high level mechanism such as feature tracking.