In
human perception
Perception () is the organization, identification, and interpretation of sensory information in order to represent and understand the presented information or environment. All perception involves signals that go through the nervous system ...
, contingent aftereffects are illusory percepts that are apparent on a test stimulus after exposure to an induction stimulus for an extended period. Contingent aftereffects can be contrasted with simple aftereffects, the latter requiring no test stimulus for the illusion/mis-perception to be apparent. Contingent aftereffects have been studied in different perceptual domains. For instance, visual contingent aftereffects, auditory contingent aftereffects and haptic contingent aftereffects have all been discovered.
An example of a visual contingent aftereffect is the
McCollough effect. The McCollough effect is one of a family of contingent aftereffects related to the processing of color and orientation. One can induce the aftereffect by exposure to a magenta and black vertical grating alternating with a green and black horizontal grating. After a few minutes of induction (5 or more is best), followed by a break of a few minutes, black-and-white vertical and horizontal gratings will appear colored. The verticals will look green and horizontals pink in the example given. Therefore, the illusory color apparent on the test fields is ''contingent'' on the orientation of the lines in that test field. Furthermore, the orientation-color contingencies present in the illusion are the ''reverse'' of those present in the adapting stimulus (i.e., the magenta-vertical and green-horizontal adaptation gratings produced illusory magenta on the horizontal test gratings and illusory green on the vertical test grating). The illusion will reverse if one rotates one's head 90°. This is because the effect is retino-topic, that is, the effect is dependent on the orientation of the test lines on the retina.
There are also color-contingent motion aftereffects,
[Favreau O.E., Emerson V.F., Corballis M.C.] and other varieties of these phenomena.
See also
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Optical illusion
Within visual perception, an optical illusion (also called a visual illusion) is an illusion caused by the visual system and characterized by a visual perception, percept that arguably appears to differ from reality. Illusions come in a wide v ...
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Visual perception
Visual perception is the ability to interpret the surrounding environment through photopic vision (daytime vision), color vision, scotopic vision (night vision), and mesopic vision (twilight vision), using light in the visible spectrum reflecte ...
References
*Favreau O.E., Emerson V.F.,
Corballis M.C. (1972) Motion Perception: A Color-Contingent Aftereffect. Science, 7, 78–79.
Optical illusions
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