Abstract
Visual neurons show fast adaptive behavior in response to brief visual input. However, the perceptual consequences of this rapid neural adaptation are not well known. Here, we show that brief exposure to a moving adaptation stimulus - ranging from tens to hundreds of milliseconds - influences the perception of a subsequently presented ambiguous motion test stimulus. Whether the ambiguous motion is perceived to move in the same direction (priming), or in the opposite direction (rapid motion aftereffect) varies systematically with the duration of the adaptation stimulus and the adaptation-test blank interval. These biases appear and decay rapidly. Moreover, when the adapting stimulus itself is ambiguous, these effects are not produced. Instead, the percept for the subsequent test stimulus is biased to the perceived direction of the adaptation stimulus. This effect (perceptual sensitization, or PS) builds gradually through longer adaptation-test intervals. The PS does not show any hint of decay as long as for 5 s - the longest interval tested. However, if a stationary pattern, instead of the blank, is viewed, the PS starts to decay after a few seconds. Our results suggest that in early motion processing, rapid adaptation serves as a rapid gain control. At a later stage, the slow potentiation controls the sensitivity depending on the past subjective perception, as opposed to input stimulus per se. This makes it tempting to suggest that this form of plastisity plays a critical role in rapid perceptual learning.