Vision is one of the most important senses available to human. The vision of the man guarantees his survival by the apprehension of danger and prey, and "takes part in a wide range of behavioural complexes: navigation, balance, object recognition, guidance of social interaction" (Harris and Humphreys, 1991, p179). Vision was a concept tackled by philosophers long before psychologists even existed, the relationship between man, vision, and the world has been one of the most studied. It is not surprising that the anatomy of the visual system is now one of the best understood. The very distinct functional specialization within this system makes it a prime example for the understanding of the brain in its whole. We will first quickly talk about the nature of visual perception before tackling the actual anatomy of the human visual system. We will then explain different methods to give evidence of the previously stated facts and the different research that led to our actual knowledge.
Humphreys and Riddock (1994) showed that 60% of the monkey's cortex is devoted to visual processing, it seems obvious that its importance is colossal. Before them Gregory (1966, p.9) already asked science the following question: "How is information from the eyes coded into neural terms, into the language of the brain, and reconstructed into experience of the surrounding objects?". It seems that we can only perceive the world. "Perception is not determined by stimulus patterns; it is a dynamic searching for the best interpretation of the available data." Gregory(1966). These available data are physical surfaces which create differential reflections of light which are then transmitted to the eye.
Rosinski (1977) categorizes perception into three di...
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...ital lobe, specialized for colour, by McKeffrey and Zeki in 1997.
Some patients face problem in space recognition: Balint (1909) describes deficits in visually guided behaviour, he calls it optic ataxia. Some patients can reach objects with their hand but not describe them. Some patients have the exact opposite problem. ( Jeannerod 1988; Perenin and Vighetto 1988; Goodale et al 1994, 1991)
The visual system is a profoundly specialized setup which analyzes the light stimuli from the visual field of both eyes. The functional segregation is based on three basic components: shape, colour and movement. Previous research in this field was based on monkeys brains, or brain damaged human patients. The anti-localization position Lashley's is no longer followed. Instead, today's research is directed towards now evidence concerning micro-specializations of the brain.
In Beau Lotto’s Ted Talk “Optical Illusions Show How We See” we could appreciate how our perception can vary based on the context. He explained the importance that color has in our lives and all of the factors that can alter how we perceive a color, such as illumination. Lotto showed how the light that comes through our eyes could mean anything, however it is our brain’s job to give meaning to that information by using patterns, associations, knowledge from past experiences, etc.
Sensory signals relating information about our physical movements, as well as information regarding external object motion, are required in order to preserve a stable and accurate view of the world, and estimate external motion. Space constancy is the visual system’s ability to maintain a view of the outside world that does not jump about and move with an eye movement (Deubel, Bridgeman, & Schneider, 1998; Stark & Bridgeman, 1983). A simple way of achieving this is to add the velocity estimates that are derived from afferent and efferent motion signals. The sum of these estimates would result in head-centred motion. For instance, the image on the retina of stationary objects in the world would gain a motion opposite and equal to any eye movement. As suggested above, reafferent retinal motion should provide a velocity estimate of similar magnitude to the efferent estimates of eye movement. If these two estimates are equal to one another, but have opposite sign, then their sum would correctly suggest null motion.
The ‘where visual pathway’ is concerned with constructing three dimensional representations of the environment and helps our brain to navigate where things are, independently of what they are, in space in relation to itself (Mishkin & Ungerleider & Macko, 1983).... ... middle of paper ... ... The 'Standard' of the 'Standard'.
Vision plays a huge role in the lives of non-human primates. Non-human primates have exceptional binocular vision, due to forward-facing eyes with overlapping visual fields (Prescott). This binocular stereoscopic color vision allows primates to see the world in terms of height, width, and depth, also known as three-dimensional vision (Haviland et al. 2010). Highly developed vision allows the later arboreal primates to judge depth, distance, and location when moving at speed from branch to branch (Haviland et al. 2010). This bino...
Gibson (1979) developed an ecological approach to the study of visual perception, which is a new and radical approach to the whole field of psychology that humans perceive their environment directly without mediation by cognitive process or by mental entities. According to his assertion of direct perception, there is enough information in our environment to make sense of the world (Gibson, 1977). Gibson (1979) said “direct perception is an activity of getting information from ambient array of light” (p. 147), and further called this a process of information pickup. That is, there is no need for mental processing since every object and event in the world have inherent meanings that are detected and exploited by humans. So his perception is based on information, not on sensations, which is in contrast with the conventional perspective of perception.
Is your life at risk and endangered if you are driving with your eyes off the road? Is it safe to walk down a dark and dangerous alley where you cannot see what is in front of you? Would it be a good idea to walk across the street without looking both ways first? The answer to all these questions are no. Why? Because in all three situations, there is a lack of vision. So, one can conclude that vision is of great importance to the visible world. Nevertheless, vision is also equally important in the invisible world. Because the most important things in our lives are invisible, vision into the invisible world is greatly needed to make life richer. The essentials to life: love, happiness, even grief and sorrow, are invisible now and forever, but vision allows us to see these and other intangible things. Vision allows us to draw the invisible world out. Unfortunately, the invisible world has always existed, except we were just too blind to see it, our visions were fogged. Likewise, the narrator from Ralph Ellison's Invisible Man is also blind. He lacks the vision he needs to realize that he is invisible to the world around him because he is naive and inexperienced. His inability to see outwardly parallels the inability to understand inwardly. However, the narrator's travel through the hero's journey is one of success. Although the narrator is invisible because he is naive, unclear of his own identity due to his fogged vision, and he assumes a series of false identities through his journey into the unknown, in the end, the narrator realizes his invisibility and begins to develop his own identity as his vision clarifies.
Blindsight is often understood as supporting certain claims concerning the function and the status of the phenomenal qualities of visual perceptions. In this talk I am going to present a short argument to show that blindsight could not be understood as evidence for these claims. The reason is that blindsight cannot be adequately described as a special case of seeing. Consequently, it is not possible to draw inferences from it concerning the role of the phenomenal qualities for seeing.
Muller, N. G., Bartelt, O. A., Donner, T. H., Villringer, A. & Brandt, S. A. (2003). A physiological correlate of the “zoom lens” of visual attention. The Journal of Neuroscience, 23(9): 3561-3565.
In A New Theory of Vision, Berkeley attempts to show that all experience is reducible to sense data by exploiting two types of argument. At times he exploits a scientific account of perception and of the functioning of the perceptual organs, while at other times he uses the argument from illusions.
In the world of man, one would think everyone sees the world in the same way. That person would be greatly mistaken. The human brain is more complex than most can believe; some would say the brain is still a modern mystery. When it comes to psychology, the idea behind perception and cognition is usually through the psyche of a ‘normal’ individual. However, some argue that studying abnormal brains, or persons with brain disorders could help better understand perception and cognition. It is correct that unusual brains can perceive differently from a standard brain. These studies can only help the scientific field expand its understanding of the brain by encompassing all brains, including those suffering from disorders. In short, brain disorders
Well, let's take a look at the brain. From being in class, my awareness about what I'm doing, what I'm seeing, what I'm hearing, what I'm thinking has come to reflect upon not just what, but how is it all being done by my brain. This morning I woke up, my eyes opened, I looked out my window, I saw the sun rising, it was this beautifully deep yellow/orange color. I thought, "How beautiful" and I smiled with a sense and feeling of wonderment. It could be said that I experienced nothing out of the ordinary this morning. Yet, if I could narrate these few activities in terms of the networking of neurons resulting in my eyes opening, my sight of the sun, my ability to perceive its color, my inner acknowledgment of its beauty and the emotions that sight evoked in me, you would be reading for a very long time and what I did this morning would indeed present itself in quite an extraordinary light. It is in recognition of this, with respect to the brain's aptitudes, that Howard Hughes in his paper, "Seeing, Hearing and Smelling the World" quoted May Pines in expressing, "We can recognize a friend instantly-full face, in profile, or even by the back of his head. We can distinguish hundreds of colors and possibly as many as 10,000 smells. We can feel a feather as it brushes our skin, hear the faint rustle of a leaf. It all seems so effortless: we open our eyes or ears and let the world stream in. Yet anything we see, hear, feel, smell, or taste requires billions of nerve cells to flash urgent messages along linked pathways and feedback loops in our brains, performing intricate calculations that scientists have only begun to decipher"(1).
There are many different Visual Perception principles in perception. The main principles are Gestalt. Gestalt is a German word meaning 'form' or 'shape'. Gestalt psychologists formulated a series of principles that describe how t...
Vision is the learned ability to see for information and performance; it allows us to understand things that we cannot touch, taste, smell or hear. 20/20 vision does not mean perfect eyesight. 20/20 vision simply means that at a 20 ft. distance a person is able to see a certain letter than an average eye should be able to see at that distance. You can have 20/20 vision and lack the abilities to use your two eyes together as a team, to judge distances, to identify colors and to coordinate your eyes with hand and body movements. About four in ten people have "perfect" vision.
Blakslee, S. (1993, August 31). The New York Times. Retrieved May 2, 2014, from www.nytimes.com: http://www.nytimes.com/1993/08/31/science/seeing-and-imagining-clues-to-the-workings-of-the-mind-s-eye.html
The Eye is the organ of sight. Eyes enable people to perform daily tasks and to learn about the world that surrounds them. Sight, or vision, is a rapidly occurring process that involves continuous interaction between the eye, the nervous system, and the brain. When someone looks at an object, what he/she is really seeing is the light that the object reflects, or gives off.