Gestalt theory proposes that people perceive objects and visual stimuli as unified wholes, rather than merely as a collection of individual parts. The psychologist Max Wertheimer developed Gestalt theory in 1910, noticing that visual meaning can change depending on cognitive interpretation. There are four principles of Gestalt systems: emergence (seeing a meaningful whole from separate pieces), reification (constructing meaning where there is none), multistability (interpreting visual information in multiple stable ways), and invariance (recognizing connections between shapes despite distortions). Together these principles help explain how people derive meaning from visual stimuli.