Psychologists have identified several "laws" of perceptual organisation on grouping which illustrate their view that the perceived whole of an object is more than the sum of its parts; that objects are interpreted as "gestalten".

Good Continuation: We tend to perceive smooth, continuous patterns rather than discontinuous ones. The pattern (right c) could be seen as a series of alternating semi-circles, but tends to be perceived as a wavy line and a straight line. Music and speech are perceived as continuous rather than a series of separate sounds.

Closure: The law of closure says that we often supply missing information to close a figure and separate it from its background. By filling in the gaps, the illustrations (right d) are seen as a triangle and a seashell.                

Part-whole relationship: As well as illustrating continuity and proximity, the three figures (right e) illustrate the principle that “the whole is greater than the sum of its parts”. Each pattern is composed of 12 crosses, but the gestalten are different, despite the similarity of the parts.

Simplicity: According to this law, stimulus pattern will be organised into its simplest components. The figure (right f) is usually perceived as a rectangle with an overlapping triangle, rather than as a complex and nameless geometric shape.

Common fate: Elements seen moving together are perceived as belonging together. This is why a group of people running in the same direction appear to be unified in their purpose.

Navons 1977 experimental test of Gestalt laws  

Navon tested the idea that the whole is perceived before the parts that make it up by presenting participants with various stimuli as shown below,

Navon distinguished between global  (or whole-like features of a stimulus) and the local (or more specific and part-like features). Each stimulus consisted of a large (global) letter made up of many small (local) letters. In some cases, the global and local letters matched (as shown in the stimulus left) and in some cases they did not (as shown on the right).     Participants had to identify either the large or small letter as quickly as possible. Navon found that the time taken to identify the large letter was unaffected by whether the small letters matched or not. However, the time taken to identify the small letters was effected by whether the large letter matched or not such that when the large letter was different, response times were longer. This suggests that it is difficult to avoid processing the whole and that global processing necessarily occurs before any more detailed perceptual analysis.