Binocular rivalry
Encyclopedia
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 a few moments, then the other, then the first, and so on, randomly
for as long as one cares to look. For example, if a set of vertical lines is presented to one eye, and a set of horizontal lines to the same region of the retina
of the other, sometimes the vertical lines are seen with no trace of the horizontal lines, and sometimes the horizontal lines are seen with no trace of the vertical lines.
At transitions, brief, unstable composites of the two images may be seen; these are often organized. For example, the vertical lines may appear one at a time to obscure the horizontal lines from the left or from the right, or the horizontal lines may appear one at a time to obscure the vertical lines from the top or from the bottom. Binocular rivalry occurs between any stimuli that differ sufficiently, including simple stimuli like lines of different orientation and complex stimuli like different alphabetic letters or different pictures such as of a face and of a house.
Very small differences between images, however, might yield singleness of vision and stereopsis
. In recent years neuroscientists have used neuroimaging
techniques and single-cell recording techniques to identify neural events responsible for the perceptual dominance of a given image and for the perceptual alternations.
es, a form of rivalry called binocular lustre
may be seen. When an image is presented to one eye and a blank field to the other, the image is usually seen continuously. This is referred to as contour dominance. Occasionally however, the blank field, or even the dark field of a closed eye, can become visible, making the image invisible for about as long as it would be invisible were it in rivalry with another image of equal stimulus strength. When an image is presented to one eye and a blank field to the other, introducing a different image onto the blank field usually results in that image being seen immediately. This is referred to as flash suppression
.
: clear, high-contrast images disappear and reappear at random. It is interesting because it is seen as a key to the ancient problem of singleness of vision: why, when we have two eyes each of which can support perception by itself, we don't see two of everything and everything is not twice as bright when we have both eyes open. It is also interesting because it's an example of the effects of attention
and top-down influences on perception, the effects of structural properties of visual stimuli and bottom-up
influences on perception, an example of bistable perception or of multistable perception
, and also as a key to finding a neural correlate of consciousness
. See Contour rivalry
.
(1593, as cited in Wade, 1996). Porta put one book in front of one eye, and another in front of the other. He reported that he could read from one book at a time and that changing from one to the other required withdrawing the "visual virtue" from one eye and moving it to the other. According to Wade (1998), binocular colour rivalry was first reported by Le Clerk (1712). Desaguiliers (1716) also recorded it when looking at different colours from spectra in the bevel of a mirror. The clearest early description of both colour and contour rivalry was made by Dutour (1760, 1763; see translations by O'Shea, 1999a, b). To experience colour rivalry Dutour either crossed his eyes or overdiverged his eyes (a form of free fusion commonly used also at the end of the 20th century to view Magic Eye
stereograms) to look at differently coloured pieces of cloth (Dutour, 1760) or differently coloured pieces of glass (Dutour, 1763). To experience contour rivalry Dutour again used free fusion of different objects or used a prism or a mirror in front of one eye to project different images into it. The first clear description of rivalry in English was by Charles Wheatstone
(e.g., 1838). Wheatstone invented the stereoscope, an optical device (in Wheatstone's case using mirrors) to present different images to the two eyes.
. Its essential idea is that we see only one of everything because the information from the two eyes is combined or fused. Wheatsone also discovered binocular stereopsis
, the perception of depth arising from the lateral placement of the eyes. Wheatstone was able to prove that stereopsis depended on the different horizontal positions (the horizontal disparity) of points in the images viewed by each eye by creating the illusion of depth from flat depictions of such images displayed in his stereoscope. Such stereopsis is impossible unless information is being combined from each eye. Although Wheatstone's discovery of stereopsis supported fusion theory, he still had to account for binocular rivalry. He regarded binocular rivalry as a special case in which fusion is impossible, saying "the mind is inattentive to impressions made on one retina when it cannot combine the impressions on the two retinae together so as to occasion a perception resembling that of some external object" (p. 264).
Other theories of binocular rivalry dealt more with how it occurs than why it occurs. Dutour speculated that the alternations could be controlled by attention
, a theory promoted in the nineteenth century by Hermann von Helmholtz
. But Dutour also speculated that the alternations could be controlled by structural properties of the images (such as by temporary fluctuations in the blur
of one image, or temporary fluctuations in the luminance
of one image). This theory was promoted in the nineteenth century by Helmholtz's traditional rival, Ewald Hering
.
Breese first found that although observers could increase the time one rival stimulus was seen by attending to it, they could not increase the rate of that stimulus. Moreover, when he asked his observers to refrain from moving their eyes over the attended stimulus, control was abolished. When he asked observers specifically to move their eyes over one stimulus, that stimulus predominated in rivalry. He could also increase predominance of a stimulus by increasing the number of its contours, by moving it, by reducing its size, by making it brighter, and by contracting the muscles on the same side of the body as the eye viewing that stimulus. Breese also showed that rivalry occurs between afterimage
s. Breese also discovered the phenomenon of monocular rivalry
: if the two rival stimuli are optically superimposed to the same eye and one fixates on the stimuli, then alternations in the clarity of the two stimuli are seen. Occasionally, one image disappears all together, as in binocular rivalry, although this is much rarer than in binocular rivalry.
and olfactory forms of perceptual rivalry can occur when there are conflicting and so rivaling inputs into the two ear
s or two nostril
s.
) on binocular rivalry.
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...
in which perception alternates between different images presented to each eye
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
.
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 a few moments, then the other, then the first, and so on, randomly
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...
for as long as one cares to look. For example, if a set of vertical lines is presented to one eye, and a set of horizontal lines to the same region of the retina
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
of the other, sometimes the vertical lines are seen with no trace of the horizontal lines, and sometimes the horizontal lines are seen with no trace of the vertical lines.
At transitions, brief, unstable composites of the two images may be seen; these are often organized. For example, the vertical lines may appear one at a time to obscure the horizontal lines from the left or from the right, or the horizontal lines may appear one at a time to obscure the vertical lines from the top or from the bottom. Binocular rivalry occurs between any stimuli that differ sufficiently, including simple stimuli like lines of different orientation and complex stimuli like different alphabetic letters or different pictures such as of a face and of a house.
Very small differences between images, however, might yield singleness of vision and stereopsis
Stereopsis
Stereopsis refers to impression of depth that is perceived when a scene is viewed with both eyes by someone with normal binocular vision. Binocular viewing of a scene creates two slightly different images of the scene in the two eyes due the the eyes' different positions on the head...
. In recent years neuroscientists have used neuroimaging
Neuroimaging
Neuroimaging includes the use of various techniques to either directly or indirectly image the structure, function/pharmacology of the brain...
techniques and single-cell recording techniques to identify neural events responsible for the perceptual dominance of a given image and for the perceptual alternations.
Types of binocular rivalry
When the images presented to the eyes differ only in their contours, rivalry is referred to as binocular contour rivalry. When the images presented to the eyes differ only in their colours, rivalry is referred to as binocular colour rivalry. When the images presented to the eyes differ only in their lightnessLuminance
Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through or is emitted from a particular area, and falls within a given solid angle. The SI unit for luminance is candela per square...
es, a form of rivalry called binocular lustre
Lustre
Lustre or Luster may refer to:* Lustre , a description of the way light interacts with the surface of a crystal, rock or mineral* Lusterware, ceramics with lustre glazes* Lustre , a Free Software distributed file system...
may be seen. When an image is presented to one eye and a blank field to the other, the image is usually seen continuously. This is referred to as contour dominance. Occasionally however, the blank field, or even the dark field of a closed eye, can become visible, making the image invisible for about as long as it would be invisible were it in rivalry with another image of equal stimulus strength. When an image is presented to one eye and a blank field to the other, introducing a different image onto the blank field usually results in that image being seen immediately. This is referred to as flash suppression
Flash suppression
Flash suppression is a phenomenon of visual perception in which an image presented to one eye is suppressed by a flash of another image presented to the other eye....
.
Why binocular rivalry is interesting
Binocular rivalry has engaged scholars since it was discovered in 1593. It is of interest for its own sake as a remarkable example of variations in consciousnessConsciousness
Consciousness is a term that refers to the relationship between the mind and the world with which it interacts. It has been defined as: subjectivity, awareness, the ability to experience or to feel, wakefulness, having a sense of selfhood, and the executive control system of the mind...
: clear, high-contrast images disappear and reappear at random. It is interesting because it is seen as a key to the ancient problem of singleness of vision: why, when we have two eyes each of which can support perception by itself, we don't see two of everything and everything is not twice as bright when we have both eyes open. It is also interesting because it's an example of the effects of attention
Attention
Attention is the cognitive process of paying attention to one aspect of the environment while ignoring others. Attention is one of the most intensely studied topics within psychology and cognitive neuroscience....
and top-down influences on perception, the effects of structural properties of visual stimuli and bottom-up
Bottom-up
Bottom-up may refer to:* In business development, a bottom-up approach means that the adviser takes the needs and wishes of the would-be entrepreneur as the starting point, rather than a market opportunity ....
influences on perception, an example of bistable perception or of multistable perception
Multistable perception
Multistable perceptual phenomena are a form of perceptual phenomena in which there are unpredictable sequences of spontaneous subjective changes...
, and also as a key to finding a neural correlate of consciousness
Neural correlates of consciousness
The neural correlates of consciousness constitute the minimal set of neuronal events and mechanisms sufficient for a specific conscious percept. Neuroscientists use empirical approaches to discover neural correlates of subjective phenomena...
. See Contour rivalry
Contour rivalry
Contour rivalry is an artistic technique used to create multiple possible visual interpretations of an image. An image may be viewed as depicting one thing when viewed in a certain way; but if the image is flipped or turned, the same lines that formed the previous image now make up an entirely new...
.
History of binocular rivalry
Binocular rivalry was discovered by PortaPorta
-People:* Porta , stagename of Christian Jiménez Bundo, a Spanish rap singer* Carlo Porta , Italian poet in the Milanese dialect* Costanzo Porta , Italian composer of the Renaissance...
(1593, as cited in Wade, 1996). Porta put one book in front of one eye, and another in front of the other. He reported that he could read from one book at a time and that changing from one to the other required withdrawing the "visual virtue" from one eye and moving it to the other. According to Wade (1998), binocular colour rivalry was first reported by Le Clerk (1712). Desaguiliers (1716) also recorded it when looking at different colours from spectra in the bevel of a mirror. The clearest early description of both colour and contour rivalry was made by Dutour (1760, 1763; see translations by O'Shea, 1999a, b). To experience colour rivalry Dutour either crossed his eyes or overdiverged his eyes (a form of free fusion commonly used also at the end of the 20th century to view Magic Eye
Magic Eye
Magic Eye is a series of books published by N.E. Thing Enterprises . The books feature autostereograms , which allow people to see 3D images by focusing on 2D patterns. The viewer must diverge his or her eyes in order to see a hidden three-dimensional image within the pattern...
stereograms) to look at differently coloured pieces of cloth (Dutour, 1760) or differently coloured pieces of glass (Dutour, 1763). To experience contour rivalry Dutour again used free fusion of different objects or used a prism or a mirror in front of one eye to project different images into it. The first clear description of rivalry in English was by Charles Wheatstone
Charles Wheatstone
Sir Charles Wheatstone FRS , was an English scientist and inventor of many scientific breakthroughs of the Victorian era, including the English concertina, the stereoscope , and the Playfair cipher...
(e.g., 1838). Wheatstone invented the stereoscope, an optical device (in Wheatstone's case using mirrors) to present different images to the two eyes.
Early theories of binocular rivalry
Various theories were proposed to account for binocular rivalry. Porta and Dutour took it as evidence for an ancient theory of visual perception that has come to be known as suppression theory. Its essential idea is that, despite having two eyes, we see only one of everything (known as singleness of vision) because we see with one eye at a time. According to this theory, we do not normally notice the alternations between the two eyes because their images are too similar. By making the images very different, Porta and Dutour argued, this natural alternation can be seen. Wheatstone, on the other hand, supported the alternative theory of singleness of vision, fusion theory, proposed by AristotleAristotle
Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...
. Its essential idea is that we see only one of everything because the information from the two eyes is combined or fused. Wheatsone also discovered binocular stereopsis
Stereopsis
Stereopsis refers to impression of depth that is perceived when a scene is viewed with both eyes by someone with normal binocular vision. Binocular viewing of a scene creates two slightly different images of the scene in the two eyes due the the eyes' different positions on the head...
, the perception of depth arising from the lateral placement of the eyes. Wheatstone was able to prove that stereopsis depended on the different horizontal positions (the horizontal disparity) of points in the images viewed by each eye by creating the illusion of depth from flat depictions of such images displayed in his stereoscope. Such stereopsis is impossible unless information is being combined from each eye. Although Wheatstone's discovery of stereopsis supported fusion theory, he still had to account for binocular rivalry. He regarded binocular rivalry as a special case in which fusion is impossible, saying "the mind is inattentive to impressions made on one retina when it cannot combine the impressions on the two retinae together so as to occasion a perception resembling that of some external object" (p. 264).
Other theories of binocular rivalry dealt more with how it occurs than why it occurs. Dutour speculated that the alternations could be controlled by attention
Attention
Attention is the cognitive process of paying attention to one aspect of the environment while ignoring others. Attention is one of the most intensely studied topics within psychology and cognitive neuroscience....
, a theory promoted in the nineteenth century by Hermann von Helmholtz
Hermann von Helmholtz
Hermann Ludwig Ferdinand von Helmholtz was a German physician and physicist who made significant contributions to several widely varied areas of modern science...
. But Dutour also speculated that the alternations could be controlled by structural properties of the images (such as by temporary fluctuations in the blur
Focus (optics)
In geometrical optics, a focus, also called an image point, is the point where light rays originating from a point on the object converge. Although the focus is conceptually a point, physically the focus has a spatial extent, called the blur circle. This non-ideal focusing may be caused by...
of one image, or temporary fluctuations in the luminance
Luminance
Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through or is emitted from a particular area, and falls within a given solid angle. The SI unit for luminance is candela per square...
of one image). This theory was promoted in the nineteenth century by Helmholtz's traditional rival, Ewald Hering
Ewald Hering
Karl Ewald Konstantin Hering was a German physiologist who did much research into color vision and spatial perception...
.
Empirical studies of binocular rivalry: B. B. Breese (1899, 1909)
The most comprehensive early study of binocular rivalry was conducted by B. B. Breese (1899, 1909). Breese quantified the amount of rivalry by requiring his observers to press keys while observing rivalry for 100-second trials. An observer pressed one key whenever and for as long as he or she saw one rival stimulus with no trace of the other, and another key whenever and for as long as he or she saw the other rival stimulus with no trace of the first. This has come to be known as recording periods of exclusive visibility. From the key-press records (Breese's were made on a kymograph drum), Breese was able to quantify rivalry in three ways: the number of periods of exclusive visibility of each stimulus (the rate of rivalry), the total duration of exclusive visibility of each stimulus, and the average duration of each period of rivalry.Breese first found that although observers could increase the time one rival stimulus was seen by attending to it, they could not increase the rate of that stimulus. Moreover, when he asked his observers to refrain from moving their eyes over the attended stimulus, control was abolished. When he asked observers specifically to move their eyes over one stimulus, that stimulus predominated in rivalry. He could also increase predominance of a stimulus by increasing the number of its contours, by moving it, by reducing its size, by making it brighter, and by contracting the muscles on the same side of the body as the eye viewing that stimulus. Breese also showed that rivalry occurs between afterimage
Afterimage
An afterimage or ghost image or image burn-in is an optical illusion that refers to an image continuing to appear in one's vision after the exposure to the original image has ceased...
s. Breese also discovered the phenomenon of 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...
: if the two rival stimuli are optically superimposed to the same eye and one fixates on the stimuli, then alternations in the clarity of the two stimuli are seen. Occasionally, one image disappears all together, as in binocular rivalry, although this is much rarer than in binocular rivalry.
Other senses
AuditoryHearing (sense)
Hearing is the ability to perceive sound by detecting vibrations through an organ such as the ear. It is one of the traditional five senses...
and olfactory forms of perceptual rivalry 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.
External links
http://www.scholarpedia.org/article/Binocular_rivalry A peer-reviewed, open-access, encyclopedia entry (ScholarpediaScholarpedia
Scholarpedia is an English-language online wiki-based encyclopedia that uses the same MediaWiki software as Wikipedia, but has features more commonly associated with open-access online academic journals....
) on binocular rivalry.
Further reading
- Wikibooks: Consciousness Studies — Effects of psilocybinPsilocybinPsilocybin is a naturally occurring psychedelic prodrug, with mind-altering effects similar to those of LSD and mescaline, after it is converted to psilocin. The effects can include altered thinking processes, perceptual distortions, an altered sense of time, and spiritual experiences, as well as...
on binocular rivalry.