Early in the 20th century, Gestalt psychologists noted certain consistencies in the way we integrate bits and pieces of sensory stimulation into meaningful wholes. This group of rules is referred to as the laws of similarity.

The Gestalt psychologists identified several principles for how we organize sensory information into meaningful patterns, including the law of similarity, but also other laws such as proximity, closure, continuity, and figure-ground. The laws of similarity is just one part of the broader Gestalt principles of perception.