Abstract
Although the speed of perceived motion in the motion aftereffect has not been extensively studied, it is generally assumed to be slower that the speed of the inducer. Here I report a dramatically faster MAE, whose speed can be 10–100 times that of the inducer. In a typical display, a field of random dots undergoes slow, coherent motion for several seconds; then, for several tens of milliseconds, the dots are re-randomized on every frame; finally, this is immediately followed once again by slow, coherent motion. During the brief burst of visual noise, observers perceive motion in the direction opposite to the inducer, and many times its speed. As opposed to the normal MAE, observers readily and reliably report displacements, which can be used to calculate speeds. Perceived displacements generally increase with noise duration, but sublinearly, implying a decelation of perceived motion. For noise durations over 100 ms, perceived displacements nearly saturate. For longer durations, the standard, slow MAE is perceived. Interestingly, one does not perceive the brief ultra-fast effect followed by slower motion, but slower motion alone, which therefore seems to mask the ultra-fast effect.