Multistable perception

Multistable perceptual phenomena are a rare form of visual perception phenomena, characterized by an unpredictable sequence of spontaneous subjective changes.

Classification

Perceptual multistability can be evoked by a large number of visual patterns that are too ambiguous for the visual system to settle down on a unique interpretation. Famous examples include the Necker cube, Structure from motion, Monocular rivalry and Binocular rivalry, but many more visually ambiguous patterns are known. Because most of these images lead to an alternation between two mutually exclusive perceptual states, they are sometimes also referred to as bistable perception.

Characterization

Transitions from one percept to its alternative are called perceptual reversals. They are spontaneous and stochastic events which cannot be eliminated by intentional efforts (although some control over the alternation process is learnable). Reversal rates vary drastically between stimuli and observers, and has been found to be slower for people with Bipolar Disorder ("sticky" interhemispheric switch in bipolar disorder).

Cultural history

Human interest in these phenomena can be traced back to antiquity. The fascination of multistable perception probably comes from the active nature of endogenous perceptual changes or from the dissociation of dynamic perception from constant sensory stimulation. In the 1980s, multistable visual patterns caught the attention of philosophers, psychologists, and neuroscientists.

Real World Examples

Photographs of craters, from either the moon or other planets including our own, can exhibit this phenomenon. Craters, in stereo imaging, such as our eyes, should appear to be pit like structures. However in mono-vision, such as that of photographs, the elimination of our depth perception causes multistable perception to take over, and this can cause the craters to inverse their depth values and instead look like plateaus rather than pits. Sometimes rotating the image so that the photographic direction of the source of light matches a light source in the room can cause the correct perception to suddenly switch, if you always seem to perceive craters as inverted mounds.

Bibliography

Alais, D & Blake, R (eds.), Binocular Rivalry, MIT Press, 2005, ISBN 026201212X
Kruse, P & Stalder, M (eds.), Ambiguity in Mind and Nature: Multistable Cognitive Phenomena, Springer, 1995, ISBN 0387570829

External links

perception | Multistabile Wahrnehmung