MOTION AFTEREFFECT WITH FLICKERING TEST PATTERNS REVEALS HIGHER STAGES OF MOTION PROCESSING

A series of experiments was conducted to clarify the distinction between motion aftereffects (MAEs) with static and counterphasing test patterns (static and flicker MAEs). It was found that while the motion of higher-order structure, such as areas defined by texture, flicker, or stereoscopic depth, induces little static MAE, such motion reliably generates flicker MAE. It was also found that static and picker MAEs were induced in opposite directions for stimuli in which first- and second-order structures moved in opposite directions (compound graftings of 2f + 3 for 2f + 3f + 4f, shifting a half cycle of 2f). When the test was static, MAE was induced in the direction opposite to the first-order motion; but when the test was counterphasing, MAE was induced in the direction opposite to the second-order motion. This means that static MAE is predominantly induced by first-order motion, but that flicker MAE is affected strongly by second-order motion, along with first-order motion. The present results suggest that static MAE primarily reflects adaptation of a low-level motion mechanism, where first-order motion is processed, while flicker MAE reveals a high-level motion processing, where both first- and second-order motion signals are available.