Visual perception

Visual perception is the ability to detect light and use it to form an image of the surrounding environment. Photodetection without image formation is classified as light sensing. In most vertebrates, visual perception can be enabled by photopic vision (daytime vision) or scotopic vision (night vision), with most vertebrates having both. Visual perception detects light (photons) in the visible spectrum reflected by objects in the environment or emitted by light sources. The visible range of light is defined by what is readily perceptible to humans, though the visual perception of non-humans often extends beyond the visual spectrum. 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 perception is an active process in which the brain interprets and organizes sensory information rather than simply recording visual input. Perception is influenced by factors such as prior knowledge, expectations, and contextual information, allowing the visual system to construct meaningful representations of the surrounding environment.…

Visual perception is the ability to detect light and use it to form an image of the surrounding environment. Photodetection without image formation is classified as light sensing. In most vertebrates, visual perception can be enabled by photopic vision (daytime vision) or scotopic vision (night vision), with most vertebrates having both. Visual perception detects light (photons) in the visible spectrum reflected by objects in the environment or emitted by light sources. The visible range of light is defined by what is readily perceptible to humans, though the visual perception of non-humans often extends beyond the visual spectrum. 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 perception is an active process in which the brain interprets and organizes sensory information rather than simply recording visual input. Perception is influenced by factors such as prior knowledge, expectations, and contextual information, allowing the visual system to construct meaningful representations of the surrounding environment. Visual perception involves not only what we see but also how our brain process information, which is also adaptive and influenced by both lifelong experience and changing cognitive capacities. ===Early studies=== (green) and ventral stream (purple) are shown. Much of the human cerebral cortex is involved in vision.]] There were two major ancient Greek schools, providing a primitive explanation of how vision works. The first was the "emission theory" of vision which maintained that vision occurs when rays emanate from the eyes and are intercepted by visual objects. If an object was seen directly it was by 'means of rays' coming out of the eyes and again falling on the object. A refracted image was, however, seen by 'means of rays' as well, which came out of the eyes, traversed through the air, and after refraction, fell on the visible object which was sighted as the result of the movement of the rays from the eye. This theory was championed by scholars who were followers of Euclid's Optics and Ptolemy's Optics. The second school advocated the so-called 'intromission' approach which sees vision as coming from something entering the eyes representative of the object. With its main propagator Aristotle (De Sensu), and his followers, this theory seems to have some contact with modern theories of what vision really is, but it remained only a speculation lacking any experimental foundation. The most decisive development of the intromission theory came from the work of the 11th-century scholar Ibn al-Haytham (Alhazen). In his Book of Optics (Kitāb al-Manāẓir, c. 1021), he rejected both the extramission theory of Euclid and Ptolemy and the purely speculative account of Aristotle. Through systematic experimentation, he demonstrated that vision occurs when light rays reflected from objects enter the eye, where they are focused by the lens onto the retina. This empirical approach marked a turning point: Alhazen not only provided the first correct explanation of vision in terms of intromission but also introduced experimental methods that influenced later European scholars such as Roger Bacon, Kepler, and eventually Newton. Both schools of thought relied upon the principle that "like is only known by like", and thus upon the notion that the eye was composed of some "internal fire" that interacted with the "external fire" of visible light and made vision possible. Plato makes this assertion in his dialogue Timaeus (45b and 46b), as does Empedocles (as reported by Aristotle in his De Sensu, DK frag. B17). : The eye has a central line and everything that reaches the eye through this central line can be seen distinctly.]] Alhazen (965 – 1040) carried out many investigations and experiments on visual perception, extended the work of Ptolemy on binocular vision, and commented on the anatomical works of Galen. He was the first person to explain that vision occurs when light bounces on an object and then is directed to one's eyes. Leonardo da Vinci (1452–1519) is believed to be the first to recognize the special optical qualities of the eye. He wrote "The function of the human eye ... was described by a large number of authors in a certain way. But I found it to be completely different." His main experimental finding was that there is only a distinct and clear vision at the line of sight—the optical line that ends at the fovea. Although he did not use these words literally he actually is the father of the modern distinction between foveal and peripheral vision. Isaac Newton (1642–1726/27) was the first to discover through experimentation, by isolating individual colors of the spectrum of light passing through a prism, that the visually perceived color of objects appeared due to the character of light the objects reflected, and that these divided colors could not be changed into any other color, which was contrary to scientific expectation of the day. ===Language model=== Following in the footsteps of George Berkeley, the Australian philosopher Colin Murray Turbayne argued in favor of an alternative to the classical "geometric model," of visual perception by asserting that aspects of it have needlessly clouded our understanding of vision since the time of Euclid. Quoting the sculptor Naum Gabo he notes: "Lines, shapes, color and movement have a language of their own, but reading takes time. It is not enough to look. you must see and "see" means "read". Turbayne argued that a "language model peculiarly illuminates this ancient problem of how we see, shedding a bright light on dark areas dimly light by its great rival." Specifically, he highlighted the limitations found within a purely mechanistic explanation of vision by arguing that several cases of "visual illusion" can be more adequately explained through the utilization of the terms found within such a language model. With this in mind, he presented a comparative analysis of specific examples of visual distortion including: the "Barrovian Case", the case of the "Horizontal Moon" and the case of the "Inverted Retinal Image."

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