FACTOID # 9: The bookmobile capital of America is Kentucky.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
   
 
WHAT'S NEW
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Binocular vision

Binocular vision is vision in which both eyes are used synchronously to produce a single image. The word binocular comes from two Latin roots, bin for two, and oculus for eye. Having two eyes confers at least two advantages over having one: it gives a creature a spare eye in case one is damaged, and it gives a wider field of view. For example, a human has a horizontal field of view with one eye of about 150 degrees and with two eyes of about 180 degrees. Vision can refer to: Visual perception is one of the senses. ... An eye is an organ that detects light. ... Latin is the language originally spoken in the region around Rome called Latium. ... Your field of view is that part of the observable world that you are able to see at any given moment. ...


Binocular vision confers at least two further advantages over monocular vision: binocular summation in which the ability to detect faint objects is enhanced, and stereopsis in which parallax provided by the two eye's different positions on the head give precise depth perception. Such binocular vision is usually accompanied by singleness of vision or binocular fusion, in which a single image is seen despite each eye's having its own image of any object. Stereopsis is the process in visual perception leading to perception of the depth or distance of objects. ... Parallax (Greek: παραλλαγή (parallagé) = alteration) is the change of angular position of two stationary points relative to each other as seen by an observer, due to the motion of said observer. ... Depth perception is the visual ability to perceive the world in three dimensions. ...


Other phenomena of binocular vision include utrocular discrimination, eye dominance, allelotropia, and binocular rivalry. Binocular rivalry is a phenomenon of visual perception. ...

Contents


Fields of view and eye movements

Some animals, usually prey animals, have their two eyes positioned on opposite sides of their heads to give the widest possible field of view. In such animals, the eyes often move independently to increase the field of view. Even without moving their eyes, some birds have a 360-degree field of view. Your field of view is that part of the observable world that you are able to see at any given moment. ... An eye is an organ that detects light. ... Prey can refer to: Look up Prey in Wiktionary, the free dictionary A prey animal eaten by a predator in an act called predation. ...


Other animals, usually predator animals, have their two eyes positioned on the front of their heads, thereby reducing field of view in favour of stereopsis. In such animals, the eyes usually move together. When the eyes move laterally, in the same direction, this is called a version. When the eyes move in opposite directions, to an object closer than where the eyes are pointing or farther than where the eyes are pointing, this is called a vergence. When the eyes move in, it is a convergence eye movement; when the eyes move out, it is a divergence eye movement. This snapping turtle is trying to make a meal of a Canada goose, but the goose is too wary. ... Stereopsis is the process in visual perception leading to perception of the depth or distance of objects. ... Generally, a version is a checkpoint at which a particular thing or idea varies from its previous state or condition. ... Convergence means approaching a definite value, as time goes on; or approaching a definite point, or a common view or opinion, or a fixed state of affairs. ... In vector calculus, the divergence is an operator that measures a vector fields tendency to originate from or converge upon a given point. ...


Some animals (including some humans, notably exotropes) use both of the above strategies. A starling, for example, has laterally placed eyes to cover a wide field of view, but can also move them together to point to the front so their fields overlap giving stereopsis. A remarkable example is the chameleon, whose eyes appear to be mounted on turrets, each moving independently of the other, up or down, left or right. Nevertheless, the chameleon can bring both of its eyes to bear on a single object when it is hunting, showing vergence and stereopsis. Genera Aplonis Poeoptera Grafisia Onychognathus Lamprotornis Cinnyricinclus Speculipastor Neochicla Spreo Cosmoparus Sarroglossa Creatophora Fregilupus (extinct) Necropsar (extinct) Sturnus Leucopsar Basilornis Streptocitta Sarcops Scissirostrum See also Myna, Oxpecker Starlings are small to medium-sized passerine birds in the family Sturnidae. ... Genera Bradypodion Calumma Chamaeleo Furcifer Brookesia Rhampholeon For alternative meanings of the word, see chameleon (disambiguation) Chameleons (family Chamaeleonidae) are small to mid-size reptiles that belong to one of the best known lizard families. ... Turret (highlighted) attached to a tower on a baronial building in Scotland In architecture, a turret (from Italian: torretta, little tower; Latin: turris, tower) is a small tower that projects from the wall of a building, such as a medieval castle or baronial house. ...


Binocular summation

Binocular summation means that the detection threshold for a stimulus is lower with two eyes than with one. There are two forms. First, when trying to detect a faint signal, there is a statistical advantage of using two detectors over using one. Mathematically, the advantage is equal to the square root of 2, about 1.41. Second, when some cells in the visual cortex receive input from both eyes simultaneously, they show binocular facilitation, a greater level of activity than the sum of the two activities evoked separately from each eye. Any advantage in using two eyes in detection task over 1.41 is credited to this sort of mechanism, dubbed neural summation. Look up Threshold in Wiktionary, the free dictionary A threshold is a fixed location or value where an abrupt change is observed. ... A stimulus is the following: In physiology, a stimulus (physiology) is something external that elicits or influences a physiological or psychological activity or response. ... The visual cortex is the general term applied to both the primary visual cortex (also known as V1) and the visual association area (V2, V3, V4, V5). ...


Binocular interaction

Apart from binocular summation, the two eyes can influence each other in at least three ways.

  • Pupillary diameter. Light falling in one eye affects the diameter of the pupils in both eyes. One can easily see this by looking at a friend's eye while her or she closes the other: when the other eye is open, the pupil of the first eye is small; when the other eye is closed, the pupil of the first eye is large.
  • Accommodation and vergence. Accommodation is the state of focus of the eye. If one eye is open and the other closed, and one focusses on something close, the accommodation of the closed eye will become the same as that of the open eye. Moreover, the closed eye will tend to converge to point at the object. Accommodation and convergence are linked by a reflex, so that one evokes the other.
  • Interocular transfer. The state of adaptation of one eye can have a small effect on the state of light adaptation of the other. Aftereffects induced through one eye can be measured through the other.

The human eye The pupil is the central transparent area (showing as black). ... The human eye The pupil is the central transparent area (showing as black). ... Adaptation may refer to— Adaptation in biology, an anatomical structure, physiological process or behavioral trait that has evolved over a period of time by the process of natural selection that increases the likelihood of reproductive success. ...

Utrocular discrimination

Utrocular discrimination is the ability to tell, when both eyes are open, to which eye a monocular stimulus was shown.


Singleness of vision

Once the fields of view overlap, there is a potential for confusion between the left and right eye's image of the same object. This can be dealt with in two ways: one image can be suppressed, so that only the other is seen, or the two images can be fused. If two images of a single object are seen, this is known as double vision or diplopia. Fusion of the images from the two eyes is considered to be separate from stereopsis for at least two reasons. First, some disorders of binocular vision, such as strabismus can spare fusion but abolish stereopsis. Second, the depth of an object either much nearer to or farther from where the eyes are fixating can be accurately judged despite the images of the object appearing double. Double Vision can refer to: Double Vision (album) - a 1978 album by Foreigner. ... Diplopia is a visual disorder that results in double vision, such that when the viewer looks at an object it seems as if there are two objects. ... Stereopsis is the process in visual perception leading to perception of the depth or distance of objects. ... Strabismus prevents bringing the gaze of both eyes to the same point in space Strabismus, also known as squint, crossed eye, wandering eye, or wall eyed, is a disorder in which the eyes do not point in the same direction. ...


Fusion of images occurs only in a small volume of visual space around where the eyes are fixating. Running through the fixation point in the horizontal plane is a curved line for which objects there fall on identical retinal points in the two eyes. This line is called the horizontal horopter. There is also a vertical horopter, which is effectively tilted away from the eyes above the fixation point and towards the eyes below the fixation point. The horizontal and vertical horopters mark the centre of the volume of singleness of vision. Within this thin, curved volume, objects nearer and farther than the horopters are seen as single. The volume is known as Panum's fusional area (it's presumably called an area because it was measured by Panum only in the horizontal plane). Outside of Panum's fusional area (volume), double vision occurs. The horopter is a 3D curve that can be defined as the set of points for which the light falls on corresponding areas in the two retinas, that is, anatomically identical points. ...


Eye dominance

When each eye has its own image of objects, it becomes impossible to align images outside of Panum's fusional area with an image inside the area. This happens when one has to point to a distant object with one's finger. When one looks at one's fingertip, it is single but there are two images of the distant object. When one looks at the distant object it is single but there are two images of one's fingertip. To point successfully, one of the double images has to take precedence and one be ignored or suppressed. The eye of the image that takes precedence is called the dominant eye. Eye dominance (sometimes called eyedness) refers to the tendency to use one eye more than the other in certain tasks involving precise hand-eye coordination and a reasonably distant target. ...


Stereopsis

Stereopsis is an ability to make fine depth discriminations from parallax provided by the two eye's different positions on the head. There are two sorts: quantitative stereopsis, in which the depth seen is very similar to the actual depth of the object being judged, and qualitative stereopsis, in which the depth is correctly nearer or father than the fixation point but the amount of depth does not grow with distance of the object from the fixation point. Quantitative stereopsis holds for small distances from the fixation plane (approximately within Panum's fusional area); qualitative stereopsis holds for larger distances from the fixation plane (outside of Panum's fusional area). Eventually an object can be moved so far from the fixation plane that there is no sense of depth of the double images--instead they appear to be on the fixation plane. Stereopsis is the process in visual perception leading to perception of the depth or distance of objects. ... Parallax (Greek: παραλλαγή (parallagé) = alteration) is the change of angular position of two stationary points relative to each other as seen by an observer, due to the motion of said observer. ...


Allelotropia

Because the eyes are in different positions on the head, any object away from fixation and off the plane of the horopter has a different visual direction in each eye. Yet when the two monocular images of the object are fused, the object has a new visual direction, essentially the average of the two monocular visual directions. This is called allelotropia. The origin of the new visual direction is a point approximately between the two eyes, the so-called cyclopean eye. The position of the cyclopean eye is not usually exactly centred between the eyes, but tends to be closer to the dominant eye.


Binocular rivalry

When very different images are shown to the same retinal regions of the two eyes, perception settles on one for a few moments, then the other, then the first, and so on, for as long as one cares to look. This alternation of perception between the images of the two eyes is called binocular rivalry. Binocular rivalry is a phenomenon of visual perception. ... Binocular rivalry is a phenomenon of visual perception. ...


Rembrandt as a person without binocular vision

People whose eyes failed to align correctly could have no binocular vision. However, to an artist, this disability could have been a gift.


In an article published on September 16, 2004 in The New England Journal of Medicine, Margaret S. Livingstone, professor of neurobiology of Harvard Medical School, suggests that Rembrandt (July 15, 1606-October 4, 1669), generally considered one of the greatest painters in European art history, suffered from this disability. She made this conclusion after having studied 36 of Rembrandt's self-portraits. September 16 is the 259th day of the year (260th in leap years). ... 2004 is a leap year starting on Thursday of the Gregorian calendar. ... The New England Journal of Medicine (NEJM) is a peer-reviewed medical journal published by the Massachusetts Medical Society. ... Neuroscience is a field of study which deals with the structure, function, development, genetics, biochemistry, physiology, pharmacology and pathology of the nervous system. ... Harvard Medical School Harvard Medical School (HMS) is one of the graduate schools of Harvard University. ... Rembrandt Harmenszoon van Rijn (July 15, 1606 – October 4, 1669) is generally considered one of the greatest painters in European art history (together with Pieter Paul Rubens), and the most important United Provinces (Netherlands) painter of the seventeenth century. ... July 15 is the 196th day (197th in leap years) of the year in the Gregorian Calendar, with 169 days remaining. ... Events January 27 - The trial of Guy Fawkes and other conspirators begins ending in their execution on January 31 May 17 - Supporters of Vasili Shusky invade the Kremlin and kill pretender Dmitri December 26 - Shakespeares King Lear performed in court Storm buries a village of St Ismails near... October 4 is the 277th day of the year (278th in Leap years). ... // Events Samuel Pepys stopped writing his diary. ... A painter is a person who paints woodwork, walls, etc. ... Medieval Art Main article: Medieval art Art during Medieval times was almost exclusively concerned with Christianity. ...


Because Rembrandt did not have normal binocular vision, his brain automatically switched to one eye for many visual tasks. This could have helped him to flatten images as he saw them, and then put them onto the two-dimensional canvas. In the author's words: In the anatomy of animals, the brain, or encephalon, is the supervisory center of the nervous system. ... Dimension (from Latin measured out) is, in essence, the number of degrees of freedom available for movement in a space. ... Canvas is an extremely heavy-duty fabric used for making sails, tents, marquees, and other functions where sturdiness is required. ...

Art teachers often instruct students to close one eye in order to flatten what they see. Therefore, stereoblindness might not be a handicap -- and might even be an asset -- for some artists.

See also: Handicap (competition) Handicapped is an adjective used to refer to a person or animal who is partially disabled or unable to use a limb or limbs. ...

See also

Binocular rivalry is a phenomenon of visual perception. ... Eye dominance (sometimes called eyedness) refers to the tendency to use one eye more than the other in certain tasks involving precise hand-eye coordination and a reasonably distant target. ... An eye is an organ that detects light. ... Your field of view is that part of the observable world that you are able to see at any given moment. ... Orthoptics is the discipline dealing with the diagnosis and treatment of defective eye coordination, binocular vision, and functional amblyopia by non-medical and non-surgical methods, e. ... Stereopsis is the process in visual perception leading to perception of the depth or distance of objects. ... Stereoscopy, stereoscopic imaging or 3-D (three-dimensional) imaging is a technique to create the illusion of depth in a photograph, movie, or other two-dimensional image, by presenting a slightly different image to each eye. ... Vision can refer to: Visual perception is one of the senses. ...

External links


  Results from FactBites:
 
NationMaster - Encyclopedia: Binocular vision (523 words)
Binocular vision is vision in which both eyes are used synchronously to produce a single image.
Binocular vision confers at least two further advantages over monocular vision: binocular summation in which the ability to detect faint objects is enhanced, and stereopsis in which parallax provided by the two eye's different positions on the head give precise depth perception.
Binocular vision (also called stereoscopic vision) is a type of visual system common in many kinds of animals where both the eyes produce only a single image in the brain.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m