Multistable perceptual phenomena are a form of perceptual phenomena in which there are unpredictable sequences of spontaneous subjective changes. While usually associated with visual perception

Visual perception

Visual perception is the ability to interpret information and surroundings from the effects of visible light reaching the eye. The resulting perception is also known as eyesight, sight, or vision...

, such phenomena can be found for auditory

Sound

Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...

 and olfactory percepts.

Classification

Perceptual multistability can be evoked by visual patterns that are too ambiguous for the human visual system

Visual system

The visual system is the part of the central nervous system which enables organisms to process visual detail, as well as enabling several non-image forming photoresponse functions. It interprets information from visible light to build a representation of the surrounding world...

 to recognise with one unique interpretation.
Famous examples include the Necker cube

Necker cube

The Necker Cube is an optical illusion first published as a rhomboid in 1832 by Swiss crystallographer Louis Albert Necker.-Ambiguity:The Necker Cube is an ambiguous line drawing....

, structure from motion

Structure from motion

In computer vision structure from motion refers to the process of finding the three-dimensional structure of an object by analyzing local motion signals over time....

, monocular rivalry

Monocular rivalry

Monocular rivalry is a phenomenon of human visual perception that occurs when two different images are optically superimposed. During prolonged viewing, one image becomes clearer than the other for a few moments, then the other image becomes clearer than the first for a few moments. These...

 and binocular rivalry

Binocular rivalry

Binocular rivalry is a phenomenon of visual perception in which perception alternates between different images presented to each eye.When one image is presented to one eye and a very different image is presented to the other, instead of the two images being seen superimposed, one image is seen for...

, but many more visually ambiguous patterns

Ambiguous image

Ambiguous images are optical illusion images which are crafted to exploit graphical similarities and other properties of visual system interpretation between two or more distinct image forms...

 are known. Since most of these images lead to an alternation between two mutually exclusive perceptual states, they are sometimes also referred to as bistable perception.

Auditory

Sound

Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...

 and olfactory examples can occur when there are conflicting and so rivaling inputs into the two ear

Ear

The ear is the organ that detects sound. It not only receives sound, but also aids in balance and body position. The ear is part of the auditory system....

s or two nostril

Nostril

A nostril is one of the two channels of the nose, from the point where they bifurcate to the external opening. In birds and mammals, they contain branched bones or cartilages called turbinates, whose function is to warm air on inhalation and remove moisture on exhalation...

s.

Characterization

Transitions from one percept to its alternative are called perceptual reversals. They are spontaneous and stochastic

Stochastic

Stochastic refers to systems whose behaviour is intrinsically non-deterministic. A stochastic process is one whose behavior is non-deterministic, in that a system's subsequent state is determined both by the process's predictable actions and by a random element. However, according to M. Kac and E...

 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

Bipolar disorder

Bipolar disorder or bipolar affective disorder, historically known as manic–depressive disorder, is a psychiatric diagnosis that describes a category of mood disorders defined by the presence of one or more episodes of abnormally elevated energy levels, cognition, and mood with or without one or...

 ("sticky" interhemispheric switch in bipolar disorder).

Cultural history

Human interest in these phenomena can be traced back to antiquity

Ancient history

Ancient history is the study of the written past from the beginning of recorded human history to the Early Middle Ages. The span of recorded history is roughly 5,000 years, with Cuneiform script, the oldest discovered form of coherent writing, from the protoliterate period around the 30th century BC...

. The fascination of multistable perception probably comes from the active nature of endogenous

Endogenous

Endogenous substances are those that originate from within an organism, tissue, or cell. Endogenous retroviruses are caused by ancient infections of germ cells in humans, mammals and other vertebrates...

 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

Netherlands

The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

 lithographer

Lithography

Lithography is a method for printing using a stone or a metal plate with a completely smooth surface...

 M. C. Escher

M. C. Escher

Maurits Cornelis Escher , usually referred to as M. C. Escher , was a Dutch graphic artist. He is known for his often mathematically inspired woodcuts, lithographs, and mezzotints...

, who was strongly influenced by mathematical physicists such as Roger Penrose

Roger Penrose

Sir Roger Penrose OM FRS is an English mathematical physicist and Emeritus Rouse Ball Professor of Mathematics at the Mathematical Institute, University of Oxford and Emeritus Fellow of Wadham College...

.

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.

A pop culture example can be found in Crow T. Robot

Crow T. Robot

Crow T. Robot is a fictional character from the American science fiction comedy television series Mystery Science Theater 3000 . Crow is a robot, who, along with others, quips and riffs upon poor-quality B movies.- Overview :...

, a puppet character on Mystery Science Theater 3000

Mystery Science Theater 3000

Mystery Science Theater 3000 is an American cult television comedy series created by Joel Hodgson and produced by Best Brains, Inc., that ran from 1988 to 1999....

. The premise of the show involves three characters (including Crow) making fun of bad movies, and as such they appear superimposed in silhouette at the bottom of the screen. Due to the design of Crow's head, it can appear that he is looking at the audience rather than at the screen.

See also

• Optical illusion
  Optical illusion
  An optical illusion is characterized by visually perceived images that differ from objective reality. The information gathered by the eye is processed in the brain to give a perception that does not tally with a physical measurement of the stimulus source...
  
  
• Experimental psychology
  Experimental psychology
  Experimental psychology is a methodological approach, rather than a subject, and encompasses varied fields within psychology. Experimental psychologists have traditionally conducted research, published articles, and taught classes on neuroscience, developmental psychology, sensation, perception,...
  
  
• Gestalt psychology
  Gestalt psychology
  Gestalt psychology or gestaltism is a theory of mind and brain of the Berlin School; the operational principle of gestalt psychology is that the brain is holistic, parallel, and analog, with self-organizing tendencies...
  
  
• Cognitive neuroscience
  Cognitive neuroscience
  Cognitive neuroscience is an academic field concerned with the scientific study of biological substrates underlying cognition, with a specific focus on the neural substrates of mental processes. It addresses the questions of how psychological/cognitive functions are produced by the brain...
  
  
• M. C. Escher
  M. C. Escher
  Maurits Cornelis Escher , usually referred to as M. C. Escher , was a Dutch graphic artist. He is known for his often mathematically inspired woodcuts, lithographs, and mezzotints...
  
  
• Salvador Dalí
  Salvador Dalí
  Salvador Domènec Felip Jacint Dalí i Domènech, Marquis de Púbol , commonly known as Salvador Dalí , was a prominent Spanish Catalan surrealist painter born in Figueres,Spain....
  
  
• Op art
  Op art
  Op art, also known as optical art, is a style of visual art that makes use of optical illusions."Optical art is a method of painting concerning the interaction between illusion and picture plane, between understanding and seeing." Op art works are abstract, with many of the better known pieces made...
  
  
• Multistability
  Multistability
  Multistability is a system property. It refers to systems that are neither stable nor totally instable, but that alternates between two or more mutually exclusive states over time....
  
  
• The Spinning Dancer
  The Spinning Dancer
  The Spinning Dancer, also known as the silhouette illusion, is a kinetic, bistable optical illusion resembling a pirouetting female dancer. The illusion, created by web designer Nobuyuki Kayahara, involves the apparent direction of motion of the figure...
  
  

External links

• VisualFunHouse Optical Illusions Multistable perception Optical Illusions
• A collection of visually ambiguous patterns
• Interhemispheric switching mediates perceptual rivalry
• Ambiguous figures Ambiguity of spatial perception (fr)