Perceptual Constancy

Perceptual Constancy is the brain's tendency to see objects as stable and unchanging even though our angle of vision and distance change as well as variations in light. There are three parts to it:

1. Size constancy: this is the perception that an object remains the same size regardless of the distance from which it is viewed.

Example: Since a constant size is kept in mind for familiar objects, the perception of two glasses on a table are the same even though the distance between them is different.

2. Shape constancy: this is the tendency to see an object as the same shape no matter what angle it is viewed from.

Example: Depending on what angle it is viewed from, the top of a mug may appear elliptical even though our brain knows it is circular.

3. Brightness constancy: this is the perception of objects  being the same color even though the light and brightness around the object may have changed.

Example: A brick wall will be perceived as brick red even though daylight fades and the actual color reflected turns gray.