Invariance

A central focus of Gestalt theory was the issue of invariance: or how the essential structural character of an object is recognized immediately and effortlessly when presented in a great variety of different aspects and viewing conditions.

For example the structures shown above left are immediately and pre-attentively recognized as the same essential shape independent of translation, rotation, and scale. And they are immediately distinguishable from those shapes on the right, which are constructed of the same essential elements.

Recognition is also invariant to distortions due to perspective and elastic deformation, as seen above left, and the structural form is even recognized when constructed of different low-level featural elements, as shown above right.

There are many more invariances and "constancies" which have been reported in perception, such as the invariance to pitch, tempo and timbre in the recognition of melodies, the phenomena that launched the Gestalt movement, lightness constancy, color constancy, size constancy, loudness constancy, position constancy, direction constancy, odor constancy, etc. These many phenomena suggest that invariance is a fundamental property of the perceptual representation.

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