Perceptual Constancy

Perception concerns the relationship between physical properties of the world and our conscious experience of them. One area of great interest to perceptual psychologists is perceptual constancy. Perceptual constancy concerns the degree to which a perception remains the same under varying conditions. Research in this area typically involves keeping some characteristic of a stimulus physically constant and asking observers to make judgments concerning that characteristic under varying contextual conditions. Researchers have studied color constancy as a function of illumination, color surround, chromatic adaptation to prolonged exposure to a color, and off-color objects known to have a specific color (such as an orange-colored cherry). Others have examined lightness constancy as a function of overall illumination, shadows, and brightness of the surround. Another area of interest is shape constancy where researchers have examined perceived shape as a function of object orientation and distance from the observer to the object. Others have looked at slant constancy as a function of object shape and configuration. Space is too limited to fully describe all aspects of perceptual constancy here, so this entry focuses in detail on the oldest and most thoroughly researched area of perceptual constancy research: size constancy.