Textbook of Usability

The Gestalt principles are a set of rules identified by early twentieth-century German psychologists (Max Wertheimer, Wolfgang Köhler, Kurt Koffka) that describe how the human visual system automatically organises individual elements into coherent groups and structures. Gestalt is German for "shape" or "form"; the movement's motto is that "the whole is greater than the sum of its parts."

The principles most relevant to interface design are:

• Proximity: elements close together are perceived as belonging together
• Similarity: elements sharing colour, shape, or size are seen as related
• Continuity: the eye follows smooth, continuous contours
• Closure: incomplete figures are perceived as whole
• Common fate: elements moving together are grouped together
• Figure and ground: scenes are separated into foreground objects and background

These principles operate automatically and unconsciously, which makes them extraordinarily powerful design tools. A form whose labels are placed near their fields (proximity) feels organised without any explicit borders. A table with alternating row colours (similarity) is easier to scan. A modal dialog with a dimmed background (figure-ground) unambiguously draws focus.

Gestalt principles can also be violated to draw attention: a single item that moves against the common fate of a group becomes conspicuous.