Perception Visual System

perceptual experience Visual SystemCritically evaluate twain key greetes to condoneing detection. cognizance is our sensory subsist of the world around us and involves credit of purlieual stimuli which allows us to act within our surroundings which is critical to our survival. thither argon twain contrasting theories which some(prenominal) seek to explore and relieve experience. These two theories are the constructivist approach and the ecological approach. Both ecological and constructionist approaches outgrowth out to explain depth perception, centre function pattern, center dust, preceding friendship of optic goals and the surrounding environment and everywhereall, give a great insight into defining perception.In order for us to understand opthalmic perception we have to look more closely at the diametrical parts of the opthalmic system to understand how the visual system works. concord to Gregory The task of the centre of attention and brain is quit e variant from either a photographic or a television camera converting quarrys merely into doubles (Atkinson, 2002. pg. 34), Gregory intelligibly explains from the aforementioned quote that the eye and the brain consists of many unlike stages from vigilant entering the eye to the eye producing the attribute to which we comprehend in the environment. The factors that mostly make up this deal are mainly consisted of the colour, movement, and brightness of the sensed public figure (Atkinson, 2002). The image below gives an indication into how the eye and its multi-different parts process lessen when entering the eye.In order for visual perception to m different place, a number of processes must occur involving the structures within the eye and the brain. The humans eye is comprised of many parts which work together to process light when entering the eye. When ocular light pricks pass through the pupil the ray of light automatically transforms into culture that the pers ons brain interprets (Wade, 2001). The cornea focuses the light on the genus Lens once light has passed through the pupil of the eye. Following on from this shout the lens then focuses the light by focusing the light crossways the patronize of the eye across the retina. Finally, the retina sends light signals to the brain via the optic tinder which is where the info is processed and depicts the image in which we see as the percipient (Wade, 2001). These steps are crucial to allowing us to celestial horizon images from the environment. Many theories reason and hypothesise how the information is really produced within the visual system.There are many theorists who argue that perception is in moot. corroborative conjecture is base upon the public opinion that perception is built upon the intervening of memories and representations as outlying(prenominal) as the environment is implicated (Gordon, 1997). This means, fit in to Gregory, that the environment provides us wit h stimulated senses which we then come across as retinene images from the opthalmic array of light, which is then processed by the visual system to produce an image from the viewed environment on the back far end of the eye (retina) to project the image recognize.Gregory (Grieve, 1986) introduced the Hypothesis system, which consort to Gregory, the signals we receive from our brain are compared with our expectation of what we expect to see and affect how an object should look like. The Hypothesis surmisal, generally assumes that we hypothesise what we see and pretend the create and size and depth of an object. Gregory (Grieve, 1986) used an grump cream as an example to prove his prefigure hike. Most of us have consumed an frost cream before, and so once we eat a future ice cream we hypothesise the fact that we may need to take precautions to non eat the ice cream in addition fast this time, if eaten fast the number 1 time on contact with this object. This simple exa mple john be used for many other objects too within the environment. No substantive evidence of psychological seek of this theory actually exists but it is a theory none the less to take into consideration when concerning the explanation of perception.Gregory (Grieve, 1986) argued merely that perception is nearly always accurate despite the absence of a limited amount of signals sent from the brain to the visual system is non always obtained properly. For example, we see and perceive objects such as a familiar bus timetable that we can see from a far outer space. We know what a bus timetable comprises of (destination, departure, and arrival times from a familiar route), although we can sole(prenominal) see a part of the timetable from the blank we make an assumption from former knowledge to complete the missing stimuli and complete the image being perceived. Gregory (Gordon, 1997) argued that what we perceive of an object image in our bear in minds changes based on introd uctory knowledge, until now the interpretation changes and not the object itself.Gregory (Bruce, 2003) withal argued further that if we understand an image furnishing an object being smaller than in reality, ponzo illusion discharge into a far distance, humans must use a pregnant amount of information interpreted from the brain to distinguish and separate the image perceived to reality, as quite obviously the smaller size of the address couldnt possibly be this small in reality and so erudition corrects this illusion. According to the direct perception theory however, direct perception theory argues that all information required for visual perception is biologically obtained from precedent knowledge which is in contrast to the indirect theory which states that new information must be processed through the visual system from the optical array of light.Gibsons perspective is based upon the direct perception theory which according to Gibson is explained in the following quote opthalmic array of light provides a direct abundance of visual information which we use to project an image of an object from the surrounding environment. (Gibson, 1986, p.g.12). What Gibson generally means from the aforementioned quote is that information of the viewed object is contained in the optic array of light in direct contact with the eye, but also that the perceiver recognises and perceives his or her own environment from biological historical senses, hence the meaning of the named, Direct perception theory. This is a process of information pick up which tends to revolve around feeling at objects distinctly and observing the environment. Gibson devised a rare study during the chancy period of knowledge base War 2, a study concerning visual perception concerning American pilot lights come an aircraft after studying training films taught by Gibson particularisation visual perception.Gibson served in the U.S air force during the dark era of World War 2. Gibson was asked by a higher serving member of the force to produce training films which involved teaching the American pilots to land an aircraft in a safe manner. Before this even in Gibsons life, he however concentrated on perception involving non-movement, which did limit Gibsons explore a light margin. Gibson tried to understand how and what pilots perceive when flying and when landing an aircraft, which led Gibson to study the subject are of perception of motion (Gibson, 1986). While conducting this field of research Gibson discovered the optic flow pattern which promoted his direct theory for further proving that his theory has the correct view point upon perception (Gibson, 1986). Optic flow pattern of course, proved to be, according to Gibson, information silklike through the optical array of light to our visual system information containing the objects and overall environment in which we see. For the pilots, this was an everyday occurrence and so became used to their environment when landing their aircraft due to prior knowledge.Gibson (Gibson, 1986) argued that the new optic flow pattern theory provides the perceiver with information regarding speed and distance of the perceived environment (pilot). The optic flow pattern come forwarded to the viewer as if the environment is moving remote from the perceiver while the perceiver remains motionless in the cockpit (environment is flowing past the perceiver while the pilot remains motionless in the aircraft). Gibsons direct perception theory as this led to the theory change integrity into three other key areas such as affordance, textured gradients and optic array. Affordance, according to Gibson, is attaching meaning to an object, such as climbing up and gobble up a ladder and driving a car as a sue for transport and so on. From this affordance theory Gibson rejected the long bound memory theory which stated that we know what objects mean from past memory.Optic array, according to Gibson, provides information about the environment from the light entering the eye to providing images to the retina section of the eye. Gibson believed that this was more automatic so to speak and provided accurate and motionless information about the object being perceived. As far as textured gradient is concerned, it was believed by Gibson that it provides information about the distance of the object and the speed or non speed of the object (Eysenck, 2005). Gibson findings from the field research concerning the American pilots produced two ingredients for further backing his theory pole and horizon. The pole is the point of direction in which the viewer is moving which is in relation to the horizon, which is concerned with the height of the perceiver. Height is extremely grievous with regards to regard objects, as name from the American pilot training research (Eysenck, 2005). The horizon from a consideration level perspective when viewing a ponzo illusion shows the two broth sin the far distance beco ming smaller and coming to a non-parallel close, where as the horizon from a pilots view when looking down shows two plain parallel lines on a continuous pattern in comparison.Gibson concluded that from his research the constructionist approach was inadequate because the viewers perception is too near perfect to be based on prior knowledge as this varies between person to person and saw perception as a very stable phenomena. Overall, Gibsons direct perception theory provided an important base for further research and developments.The two theories contrast each other when explaining depth perception. The ecological view argues that depth perception is perceived by biological cues which, for example, could be height in the field viewing the horizon. The pilot training experiment stock-still again proves to be a full(a) example to use for aerial perception. (Objects are higher in the distance than nearby objects), texture gradients (faded objects in the distance).The constructionist view of perception argues for a different point of view. According to indirect perception theory, depth perception is simply possible for the simple reason that objects are constant in shape and size and is unrealizable to just change appearance within the perceived environment (Schiffman, 2000). Relative size, according to indirect perception theory, gives an overview that although we may perceive different objects in the environment, different retinal images are produced from the different distance between each object, such as perceiving a different retinal image of the far end of the ponzo illusion although perceive the correct view at the nearest point of view to us. The two theories differ on their views when explaining the topic of visual illusions.The constructionists argue that we see three-dimensional illusion objects over 2 dimensional objects because the visual system and the brain perceives three-dimensional objects as a simpler object to project rather than two dimen sional objects (Farah, 2000). insight perception is key here as to the size, shape and the shadow answer that the object gives off during perceiving of the object. Critics have commented on the possible fact that the constructivist approach gives a computational feel effect when explaining and defending its theory (Farah, 2000). However, both theories are seen as computational, the difference is that the constructivists appear to process information that has goose egg to do with sensory stimulation while the ecological approach however, flaws itself by only when concentrating information found in stimulation completely argue the constructionist approach towards perception.Visual illusions work because the view we have is often of a very short time and usually two dimensional. However, the constructionist only go so far in understanding seeing and not far enough in explaining how people assign meaning to illusions much is yet to be explained further.The Necker cube is a good exa mple of a visual illusion. As you can see from figure 2, when two lines cross, the picture does not show which is in front and which is behind. This makes the picture ambiguous it can be interpreted two different ways. When a person stares at the picture, it entrust often seem to flip back and forth between the two valid interpretations, known as multi-stable perception (Humphrey, 1989). This illusion gives the impression that no sides of the cube are at all missing and that what the viewer is seeing is true. However, if you was to ignore prior knowledge, expectation, and assumption and viewed the cube from a total different angle you would come to the conclusion that the cube isnt what it appears to be as perceived. display the figure picture from a certain perception point of view, it would appear that the cube is defying the laws of geometry. However, once the point of perception is changed to another angle we can clearly see that, from figure 1, it becomes clear that the beams are not satisfying as once thought (Eysenck, 2005). The illusion plays on the humans eye interpretation of two-dimensional pictures as three-dimensional objects. This apparent solidity gives the impossible cube greater visual ambiguity than the Necker cube, which is less likely to be perceived as an impossible object. This wrong view of the cube on the left is also a good example of how wrong or flawed a theory can be due to the prior knowledge of objects from the hypothesis theory by Gregory (1966).In conclusion, indirect perception believes that perception is built upon the fact that our visual system produces memories and representations of the environment which intervenes when viewing an object and the environment as a whole. Indirect theory also concludes that the (Hypothesis theory) the signals we receive from our brain are compared with our overall expectations of the presumed environment, along with our visual system predicting how a shape and size of an object should look like. Indirect theory also further concluded that prior knowledge and experience of an object helps us how to perceive it once more from viewing the object in the past (bus timetable) from a far distance.However, Gibsons direct perception theory can be concluded that from Gibsons own personal research, perception is based upon the optical flow pattern which contains the array of light, attached with it, information essential to reproduce this viewed environment from any angle and distance. Pole position from Gibsons research showed an illusion where the aircraft appeared to be motionless while the environmental moved past and around the aircraft, this produced the temptation for future researchers to investigate the subject of motion. Both theories show an intriguing insight into perception, however, neither one of the aforementioned theories appear to explain how the visual system works, as each theory is flawed and only produced a speculation into how the visual system functions. With future theories waiting to be introduced we may finally be able to answer the question, how does the visual system work?.References1. Atkinson, J. (2002) The Developing Visual Brain. Oxford Oxford University Press2. Bruce, V. (2003) Visual Perception Physiology, psychology and Ecology. 4th edition, Hove Psychology Press.3. (2005)Necker Cube Experiment. Available at http//www.bbc.co.uk/apps/ifl/science/humanbody/mind/surveys/neckercube/decision?_next=index_1.tmpl(Accessed on 18th January 2008).4. Eysenck, M and Keane, M. (2005) Cognitive Psychology A students handbook, 5th Ed. Psychology Press.5. Farah, M. (2000) The Cognitive Neuroscience of Vision. Oxford Blackwell Publishers.6. Gibson, J (1986) The ecological approach to visual perception. London Lawrence Erlbaum Associates.8. Grieve, J. (1986) Neuropsychology for occupational therapists assessment of perception and cognition, 2nd edition. Oxford Blackwell acquirement9. Gordon, I (1997) Theories of Visual Perception. Chich ester Wiley.10. Humphrey, G. (1989) Visual Cognition Computational Experimental and neuropsychological Perspectives, Hove Lawrence Erlbaum Associates.11. Necker Cube and Impossible Cube. Available at http//www.thebestlinks.com/Image__3A__Necker_cube_and_impossible_cube.PNG.html(Accessed on 18th January 2008)12. Paterson, A. (2005) Perception and Visual Cognition. Available at http//www.psy.gla.ac.uk/martinl/Assets/PVC/PVCL3ML.pdf (Accessed on 16th January 2008)13. Schiffman, H. (2000) sorcerer and perception an integrated approach, 5th edition. New York Wiley.14. Wade, N (2001) Visual Perception an introduction. Hove Psychology Press.