motion aftereffect

    (MAE)

   A term used to denote a type of aftereffect characterized by illusory motion. The American experimental psychologists George Mather et al. define the MAE as "the illusory movement of a physically stationary scene following exposure to visual motion". The Greek philosopher Aristotle (384-322 BC) has been credited with providing the oldest known description of an MAE (more specifically, the * river illusion, which is considered phenomenologically similar to the * waterfall effect) in his book Parva Naturalia. MAEs typically occur after viewing a moving pattern for a prolonged period of time and then shifting one's gaze to a stationary background. That background then appears to move in the opposite direction. This order of events is interpreted as an indication that it is possible for the motionsensitive cells within the visual system to adapt to movement, while the position-sensitive cells remain unaffected. The neurophysiological correlates of the MAE are not fully understood. It has been suggested that at least two types of mechanisms may be responsible for their mediation, i.e. a peripheral mechanism capable of mediating monocular MAEs, and a central mechanism capable of mediating the interocular transfer of MAEs, which may result in the binocular perception of illusory movement. Some models of physiological motion detection attribute the mediation of centrally evoked MAEs to the adaptation of single cells or cell columns within the visual cortex (striate as well as extrastriate) to the specific type of movement involved. A competing set of models, known by the umbrella term 'ratio model', attribute the mediation ofMAEs to multiple gain controls, exerted by various parts of the visual system. A third hypothesis is known as the recurrent inhibition model. The MAE is commonly classified as a *physiological illusion.

   References

   Mather, G., Verstraten, F., Anstis, S. (1998). The motion aftereffect: A modern perspective. Cambridge, MA: MIT Press.

   Verstraten, F.A.J. (1996). On the ancient history of the direction of the motion aftereffect. Perception, 25, 1177-1187.