Light
Shape refers to the visual characteristic of an object that remains consistent regardless of its position or orientation. It is the overall form or outline of an object.
Perceptual constancy is the tendency to perceive objects as having stable properties such as size, shape, and color despite changes in sensory input.
Visual illusions are misinterpretations or distortions of real-world stimuli that can result in perceiving something differently than it actually is.
The figure-ground relationship refers to our ability to distinguish between an object (figure) and its surrounding background (ground).