Binocular rivalry

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Binocular rivalry is a phenomenon of visual perception in which perception alternates between different images presented to each eye. [1]

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An image demonstrating binocular rivalry. If you view the image with red-cyan 3D glasses, the text will alternate between Red and Blue. 3D red cyan glasses are recommended to view this image correctly. BinocularRivalry.svg
An image demonstrating binocular rivalry. If you view the image with red-cyan 3D glasses, the text will alternate between Red and Blue. 3d glasses red cyan.svg 3D red cyan glasses are recommended to view this image correctly.
Binocular rivalry. If you view the image with red-cyan 3D glasses, the angled Warp and weft will alternate between the Red and the Blue lines. 3D red cyan glasses are recommended to view this image correctly. Binocular rivalry.jpg
Binocular rivalry. If you view the image with red-cyan 3D glasses, the angled Warp and weft will alternate between the Red and the Blue lines. 3d glasses red cyan.svg 3D red cyan glasses are recommended to view this image correctly.

When one image is presented to one eye and a very different image is presented to the other (also known as dichoptic presentation), instead of the two images being seen superimposed, one image is seen for a few moments, [2] 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. For example, the vertical lines may appear one at a time to obscure the horizontal lines from the left or from the right, like a traveling wave, switching slowly one image for the other. [3] Binocular rivalry occurs between any stimuli that differ sufficiently, [4] 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. Binocular rivalry has been extensively studied in the last century. [5] [ page needed ] In recent years[ when? ] 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.

Types

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 lightnesses, 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 .

History

Binocular rivalry was discovered by Porta. [6] 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 Clerc (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 ). 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 CharlesWheatstone  ( 1838 ). Wheatstone invented the stereoscope, an optical device (in Wheatstone's case using mirrors) to present different images to the two eyes.

Early theories

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 Aristotle. Its essential idea is that we see only one of everything because the information from the two eyes is combined or fused. Wheatstone 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).[ full citation needed ]

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.[ full citation needed ] 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.[ full citation needed ]

Empirical studies: 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 afterimages. 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 altogether, as in binocular rivalry, although this is much rarer than in binocular rivalry.

Other senses

Auditory and olfactory forms of perceptual rivalry can occur when there are conflicting and so rivaling inputs into the two ears [7] or two nostrils. [8]

See also

Related Research Articles

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In biology, binocular vision is a type of vision in which an animal has two eyes capable of facing the same direction to perceive a single three-dimensional image of its surroundings. Binocular vision does not typically refer to vision where an animal has eyes on opposite sides of its head and shares no field of view between them, like in some animals.

<span class="mw-page-title-main">Depth perception</span> Visual ability to perceive the world in 3D

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<span class="mw-page-title-main">Autostereogram</span> Visual illusion of 3D scene achieved by unfocusing eyes when viewing specific 2D images

An autostereogram is a two-dimensional (2D) image that can create the optical illusion of a three-dimensional (3D) scene. Autostereograms use only one image to accomplish the effect while normal stereograms require two. The 3D scene in an autostereogram is often unrecognizable until it is viewed properly, unlike typical stereograms. Viewing any kind of stereogram properly may cause the viewer to experience vergence-accommodation conflict.

<span class="mw-page-title-main">Monocular rivalry</span> Optical illusion

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 alternations in clarity continue at random for as long as one looks. Occasionally one image will become exclusively visible and the other image invisible.

The McCollough effect is a phenomenon of human visual perception in which colorless gratings appear colored contingent on the orientation of the gratings. It is an aftereffect requiring a period of induction to produce it. For example, if someone alternately looks at a red horizontal grating and a green vertical grating for a few minutes, a black-and-white horizontal grating will then look greenish and a black-and-white vertical grating will then look pinkish. The effect is remarkable because, although it diminishes rapidly with repeated testing, it has been reported to last up to 2.8 months when exposure to testing is limited.

Random-dot stereogram (RDS) is stereo pair of images of random dots which, when viewed with the aid of a stereoscope, or with the eyes focused on a point in front of or behind the images, produces a sensation of depth, with objects appearing to be in front of or behind the display level.

<span class="mw-page-title-main">Cyclopean image</span>

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Stereopsis is the component of depth perception retrieved through binocular vision. Stereopsis is not the only contributor to depth perception, but it is a major one. Binocular vision happens because each eye receives a different image because they are in slightly different positions on one's head. These positional differences are referred to as "horizontal disparities" or, more generally, "binocular disparities". Disparities are processed in the visual cortex of the brain to yield depth perception. While binocular disparities are naturally present when viewing a real three-dimensional scene with two eyes, they can also be simulated by artificially presenting two different images separately to each eye using a method called stereoscopy. The perception of depth in such cases is also referred to as "stereoscopic depth".

<span class="mw-page-title-main">Horopter</span>

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<span class="mw-page-title-main">Motion-induced blindness</span> Optical illusion

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Stereoblindness is the inability to see in 3D using stereopsis, or stereo vision, resulting in an inability to perceive stereoscopic depth by combining and comparing images from the two eyes.

<span class="mw-page-title-main">Chromostereopsis</span> Visual illusion whereby the impression of depth is conveyed in two-dimensional color images

Chromostereopsis is a visual illusion whereby the impression of depth is conveyed in two-dimensional color images, usually of red–blue or red–green colors, but can also be perceived with red–grey or blue–grey images. Such illusions have been reported for over a century and have generally been attributed to some form of chromatic aberration.

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Continuous flash suppression (CFS) is an adapted version of the original flash suppression method, first reported in 2004. In CFS, the first eye is presented with a static stimulus, such as a schematic face, while the second eye is presented with a series of rapidly changing stimuli. The result is the static stimulus becomes consciously repressed by the stimuli presented in the second eye. A variant of CFS to suppress a dynamic stimulus is also reported

Binocular neurons are neurons in the visual system that assist in the creation of stereopsis from binocular disparity. They have been found in the primary visual cortex where the initial stage of binocular convergence begins. Binocular neurons receive inputs from both the right and left eyes and integrate the signals together to create a perception of depth.

Stereoscopic motion, as introduced by Béla Julesz in his book Foundations of Cyclopean Perception of 1971, is a translational motion of figure boundaries defined by changes in binocular disparity over time in a real-life 3D scene, a 3D film or other stereoscopic scene. This translational motion gives rise to a mental representation of three dimensional motion created in the brain on the basis of the binocular motion stimuli. Whereas the motion stimuli as presented to the eyes have a different direction for each eye, the stereoscopic motion is perceived as yet another direction on the basis of the views of both eyes taken together. Stereoscopic motion, as it is perceived by the brain, is also referred to as cyclopean motion, and the processing of visual input that takes place in the visual system relating to stereoscopic motion is called stereoscopic motion processing.

Binocular rivalry is a visual phenomenon wherein one experiences alternating perceptions due to the occurrence of different stimuli presented to the corresponding retinal regions of the two eyes and their competition for perceptual dominance.

Binocular switch suppression (BSS) is a technique to suppress usually salient images from an individual's awareness, a type of experimental manipulation used in visual perception and cognitive neuroscience. In BSS, two images of differing signal strengths are repetitively switched between the left and right eye at a constant rate of 1 Hertz. During this process of switching, the image of lower contrast and signal strength is perceptually suppressed for a period of time.

References

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  6. Porta 1593, as cited in Wade 1996
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Further reading