Multistable perception
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Multistable perceptual phenomena are a rare form of visual perception phenomena, characterized by an unpredictable sequence of spontaneous subjective changes.
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[edit] 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.
[edit] 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) [1].
'Impossible objects' exist as two dimensional vectors which can be defined by Cartesian Coordinate systems. As such, the 'objects' do not exist as 'true three dimensional forms', and in this context are identical to the perception of 'paint' on a wall, that is: 'color'. Or, similarly, a 'skin' defining form. Thus, 'impossible objects' can be defined as a 'visual' tautology, the ambiguity of the apparent object being nothing more than the result of self-referential perceptual conventions.
[edit] 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. Multistable perception was a common feature in the artwork of the Dutch lithographer M. C. Escher, who was strongly influenced by mathematical physicists such as Roger Penrose. Two of his most famous works, Ascending and Descending and Waterfall, being adaptations of the Penrose triangle.
[edit] 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.
A famous pop culture version can be seen on the TV series Mystery Science Theater 3000; during the theater segments, many people claim Crow T. Robot faces away from the movie screen rather than towards it because of multistable perception. The question has been asked enough times that Best Brains addressed it in the FAQ section of the Amazing Colossal Episode Guide.
[edit] See also
- Optical illusion
- Experimental Psychology
- Gestalt Psychology
- Cognitive neuroscience
- M.C. Escher
- Salvador Dalí
- Op art
- Structure from motion
[edit] Bibliography
- Alais, D & Blake, R (eds.), Binocular Rivalry, MIT Press, 2005, ISBN 0-262-01212-X
- Kruse, P & Stalder, M (eds.), Ambiguity in Mind and Nature: Multistable Cognitive Phenomena, Springer, 1995, ISBN 0-387-57082-9
[edit] Sources
- ^ Miller, S; Gynther B, Heslop K, Liu G, Mitchell P, Ngo T, Pettigrew J, Geffen L (2003). "Slow binocular rivalry in bipolar disorder". Psychological Medicine 33: 683?92.
