constancy

constancy

[kon′stənsē]

an absence of variation in quality of distinctive features despite location, rotation, size, or color of an object.

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constancy 

Perceptual phenomenon whereby the properties of certain objects appear to remain relatively constant, despite changes in the stimulus characteristics which induced the perception. All constancies occur only within a limited range.
brightness constancy Perceptual phenomenon whereby the brightness of an object appears to remain relatively constant, despite changes in the level of its illumination. Example: white paper appears white whether it is seen in sunlight or in the weaker or yellower illumination of a light bulb. Syn. lightness constancy.
colour constancy Perceptual phenomenon whereby the colour of an object appears to remain relatively constant, despite changes in the spectral composition of the incident light.
shape constancy Perceptual phenomenon whereby the shape of an object appears to remain relatively constant, despite changes in the viewing angle. Example: A circle held obliquely to the line of sight appears more circular than it should due to shape constancy although its retinal projection is oval.
size constancy Perceptual phenomenon whereby the size of an object appears to remain relatively constant, despite changes in the viewing distance (and therefore of its retinal image size).