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Crowding
Crowding (or visual crowding) is a perceptual phenomenon where the recognition of objects presented away from the fovea is impaired by the presence of other neighbouring objects (sometimes called "flankers"). It has been suggested that crowding occurs due to mandatory integration of the crowded objects by a texture-processing neural mechanism, but there are several competing theories about the underlying mechanisms. It is considered a kind of grouping since it is "a form of integration over space as target features are spuriously combined with flanker features." Crowding has long been thought to be predominantly a characteristic of peripheral vision. Yet, while it is indeed particularly prominent there, it is present in the whole of the visual field, with only its spatial extent varying (governed by Bouma's law; see below). In particular, crowding is of utmost importance in foveal vision, overriding the importance of visual acuity in pattern recognition and reading where crowd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Visual Acuity
Visual acuity (VA) commonly refers to the clarity of vision, but technically rates an examinee's ability to recognize small details with precision. Visual acuity is dependent on optical and neural factors, i.e. (1) the sharpness of the retinal image within the eye, (2) the health and functioning of the retina, and (3) the sensitivity of the interpretative faculty of the brain. The most commonly referred visual acuity is the far acuity (e.g. 6/6 or 20/20 acuity), which describes the examinee's ability to recognize small details at a far distance, and is relevant to people with myopia; however, for people with hyperopia, the near acuity is used instead to describe the examinee's ability to recognize small details at a near distance. A common cause of low visual acuity is refractive error (ametropia), errors in how the light is refracted in the eyeball, and errors in how the retinal image is interpreted by the brain. The latter is the primary cause for low vision in people with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herman Bouma
Herman Bouma (born 15 March 1934) is a Dutch vision researcher and gerontechnologist. He is considered to be one of the founders of the field of gerontechnology. He spent the majority of his career at the Institute of Perception Research, serving as its director from the mid-1970s until 1994. He subsequently led the Institute for Gerontechnology until 1999. A perceptual law, based on a publication of his in 1970 is named Crowding#, ''Bouma's Law'' in his honour. Career Bouma was born in Harderwijk on 15 March 1934. He obtained a degree in physics from Utrecht University and also partially studied medicine there. In 1959 Bouma started working for the Institute of Perception Research (Dutch:''Instituut voor Perceptie Onderzoek'', IPO), an institute of Philips Natuurkundig Laboratorium, Philips Research and the Eindhoven University of Technology. In 1965 he obtained his PhD at Eindhoven University of Technology under Jan Frederik Schouten with a thesis titled: "Receptive systems mediati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eye Chart
__NOTOC__ An eye chart, or optotype, is a chart used to subjectively measure visual acuity. Eye charts are often used by health care professionals, such as optometrists, physicians or nurses, to screen persons for vision impairment. Ophthalmologists, physicians who specialize in the eye, also use eye charts to monitor the visual acuity of their patients in response to various therapies such as medications or surgery. The chart is placed at a standardized distance away from the person whose vision is being tested. The person then attempts to identify the symbols on the chart, starting with the larger symbols and continuing with progressively smaller symbols until the person cannot identify the symbols. The smallest symbols that can be reliably identified is considered the person's visual acuity. The Snellen chart is the most widely used. Alternative types of eye charts include the logMAR chart, Landolt C, E chart, Lea test, Golovin–Sivtsev table, the Rosenbaum chart, and the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peripheral Vision
Peripheral vision, or ''indirect vision'', is vision as it occurs outside the point of fixation, i.e. away from the center of gaze or, when viewed at large angles, in (or out of) the "corner of one's eye". The vast majority of the area in the visual field is included in the notion of peripheral vision. "Far peripheral" vision refers to the area at the edges of the visual field, "mid-peripheral" vision refers to medium eccentricities, and "near-peripheral", sometimes referred to as "para-central" vision, exists adjacent to the center of gaze. Boundaries Inner boundaries The inner boundaries of peripheral vision can be defined in any of several ways depending on the context. In everyday language the term "peripheral vision" is often used to refer to what in technical usage would be called "far peripheral vision." This is vision outside of the range of stereoscopic vision. It can be conceived as bounded at the center by a circle 60° in radius or 120° in diameter, centered aro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amblyopia
Amblyopia, also called lazy eye, is a disorder of sight in which the brain fails to fully process input from one eye and over time favors the other eye. It results in decreased vision in an eye that typically appears normal in other aspects. Amblyopia is the most common cause of decreased vision in a single eye among children and younger adults. The cause of amblyopia can be any condition that interferes with focusing during early childhood. This can occur from poor alignment of the eyes (strabismic), an eye being irregularly shaped such that focusing is difficult, one eye being more nearsighted or farsighted than the other (refractive), or clouding of the lens of an eye (deprivational). After the underlying cause is addressed, vision is not restored right away, as the mechanism also involves the brain. Amblyopia can be difficult to detect, so vision testing is recommended for all children around the ages of four to five. Early detection improves treatment success. Glasse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ricco's Law
Riccò's law, discovered by astronomer Annibale Riccò, is one of several laws that describe a human's ability to visually detect targets on a uniform background. This law explains the visual relationship between a target angular area ''A'' and target luminance increment \Delta L required for detection when that target is unresolved (that is, is too small in the field of view to make out different parts of it). The law is given by: :\mathrm \Delta L = \frac k where k is a constant (for a given background, see below). For constant background luminance L, the equation can be restated as :\Delta L / L = C = \frac K with a different constant K. The fraction \Delta L / L is referred to as Weber contrast ''C''. Riccò's law is applicable for regions where the target being detected is unresolved. The resolution of the human eye (the receptive field size) is approximately one arc-minute in the center (the fovea center) but the size increases in peripheral vision. Riccò's law is a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Visual Perception
Visual perception is the ability to interpret the surrounding Biophysical environment, environment through photopic vision (daytime vision), color vision, scotopic vision (night vision), and mesopic vision (twilight vision), using light in the visible spectrum reflected by objects in the environment. This is different from visual acuity, which refers to how clearly a person sees (for example "20/20 vision"). A person can have problems with visual perceptual processing even if they have 20/20 vision. The resulting perception is also known as vision, sight, or eyesight (adjectives ''visual'', ''optical'', and ''ocular'', respectively). The various physiological components involved in vision are referred to collectively as the visual system, and are the focus of much research in linguistics, psychology, cognitive science, neuroscience, and molecular biology, collectively referred to as vision science. Visual system In humans and a number of other mammals, light enters the eye t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Object Recognition And Categorization
Object recognition – technology in the field of computer vision for finding and identifying objects in an image or video sequence. Humans recognize a multitude of objects in images with little effort, despite the fact that the image of the objects may vary somewhat in different view points, in many different sizes and scales or even when they are translated or rotated. Objects can even be recognized when they are partially obstructed from view. This task is still a challenge for computer vision systems. Many approaches to the task have been implemented over multiple decades. Approaches based on CAD-like object models * Edge detection * Primal sketch * Marr, Mohan and Nevatia * Lowe * Olivier Faugeras Recognition by parts * Generalized cylinders (Thomas Binford) * Geons ( Irving Biederman) * Dickinson, Forsyth and Ponce Appearance-based methods * Use example images (called templates or exemplars) of the objects to perform recognition * Objects look different ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daniel Kahneman
Daniel Kahneman (; he, דניאל כהנמן; born March 5, 1934) is an Israeli-American psychologist and economist notable for his work on the psychology of judgment and decision-making, as well as behavioral economics, for which he was awarded the 2002 Nobel Memorial Prize in Economic Sciences (shared with Vernon L. Smith). His empirical findings challenge the assumption of human rationality prevailing in modern economic theory. With Amos Tversky and others, Kahneman established a cognitive basis for common human errors that arise from heuristics and biases, and developed prospect theory. In 2011 he was named by '' Foreign Policy'' magazine in its list of top global thinkers. In the same year his book '' Thinking, Fast and Slow'', which summarizes much of his research, was published and became a best seller. In 2015, ''The Economist'' listed him as the seventh most influential economist in the world. He is professor emeritus of psychology and public affairs at Princeton ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carl Friedrich Richard Förster
Carl Friedrich Richard Förster (15 November 1825 – 7 July 1902) was a German ophthalmologist born in the town of Lissa (today Leszno, Poland). He received his medical doctorate in 1849, and for most of his career was associated with the University of Breslau. Two of his assistants at Breslau were Hermann Wilbrand (1851–1935) and Hermann Rudolph Aubert (1826–1892). Förster is remembered for conducting tests of visual acuity, and for his investigations of indirect vision (peripheral vision) and visual performance across the visual field together with Hermann Aubert. The linear variation of visual performance that they described is sometimes referred to as the Aubert-Foerster law. From Förster's research, the eponymous terms of "Förster perimeter" and "Förster's shift" are derived. A Förster perimeter was an instrument used to measure an individual's field of vision. He also devised a specialized photometer to determine the smallest amount of light that will permit an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hermann Rudolph Aubert
Hermann Rudolph Aubert (November 23, 1826 – February 2, 1892) was a German physiologist born in Frankfurt. In 1850 he obtained his medical doctorate, afterwards serving as privat-docent of physiology at Breslau (1854). In 1862 he became an associate professor, later being appointed professor of physiology at the University of Rostock (1865). Aubert is known for his research involving psychophysics, including the way an observer perceives pattern, movement and orientation. He conducted several experiments involving the phenomenon of dark adaptation; namely the eye's ability to regain its sensitivity in the dark after it had been exposed to bright lights. With ophthalmologist Richard Förster (1825–1902), he performed a series of tests on vision outside the point of fixation, which they referred to as indirect vision. Their findings were published in a treatise called ''Beiträge zur Kenntniss des indirecten Sehens'' (1857). From their work the eponymous "Aubert-Förste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
James Jurin
James Jurin FRS FRCP (baptised 15 December 168429 March 1750) was an English scientist and physician, particularly remembered for his early work in capillary action and in the epidemiology of smallpox vaccination. He was a staunch proponent of the work of Sir Isaac Newton and often used his gift for satire in Newton's defence. Early life Jurin's father was John Jurin, a London dyer. His mother was John's wife Dorcas Cotesworth. He was educated at Christ's Hospital where he won a scholarship to Trinity College, Cambridge, graduating BA in 1705, and being elected fellow the following year. Becoming the ''protégé'' of the master of Trinity, Richard Bentley, Jurin became tutor to Mordecai Cary, travelling with him internationally. Jurin achieved his MA in 1709 and became headteacher of the Royal Grammar School, Newcastle. Jurin became a frequent public speaker on mathematics and the work of Sir Isaac Newton. Jurin returned to Cambridge in 1715 to study medicine, becoming MD ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
