Research

Rapid Adaptation

Perceptual aftereffects have been demonstrated following long periods of adaptation to stimuli ranging from low-level visual features like orientation and motion, all the way up to complex stimuli like faces, but this represents several orders of magnitude more exposure than in an average eye fixation. Given the dynamic nature of the visual world, it seems unlikely that the kind of adaptation shown in these studies impacts everyday vision.

Conversely, neural adaptation has been demonstrated in single units following just tens of milliseconds of stimulation in both early and extrastriate visual areas. We have shown a perceptual aftereffect (the motion aftereffect) on similar timescales, suggesting that perceptual adaptation represents a potentially important influence on vision, rather than a source of illusions only relevant in the laboratory.

• Glasser, D.M., Tsui, J.M.G., Pack, C.C., & Tadin, D. (2011). Perceptual and neural consequences of rapid motion adaptation. Proceedings of the National Academy of Sciences, 108(45), E1080-E1088. [pdf] [Author Summary]
  
  We demonstrated that 25 ms of motion adaptation is sufficient to generate the motion aftereffect (MAE), even when the subjects were unable to discriminate the motion of the adapting stimuli. In single-cell recordings from cortical area MT, we found that this brief motion adaptation evokes direction-selective responses to subsequently presented stationary stimuli.

Cue Combination in Motion Perception

It is well established that multiple systems sensitive to different cues subserve motion perception. While there is evidence that these systems may not directly share information, it seems reasonable that an observer would combine readouts from the various systems when trying to accurately discriminate motion. This process has not received much investigation, presumably for two reasons: (1) because these cues are usually highly correlated within stimuli, and (2) because first-order motion cues typically dominate perception when they are present. Indeed, much of what is known about the spatial and temporal properties of second-order and attentional tracking mechanisms comes from studies that went to great lengths to minimize or eliminate first-order information. Experimentally modifying subjects' sensitivity to different motion cues should yield considerable insight into how these cues are combined.

• Glasser, D.M. & Tadin, D. (2011). Increasing stimulus size impairs first- but not second-order motion perception. Journal of Vision, 11(13): 22:1-8. [pdf]