The ultimate goal for a system of visual perception is representing visual scenes. It is generally assumed that this requires an initial ‘break-down’ of complex visual stimuli into some kind of “discrete subunits” (De Valois & De Valois, 1980, p.316) which can then be passed on and further processed by the brain. The task thus arises of identifying these subunits as well as the means by which the visual system interprets and processes sensory input. An approach to visual scene analysis that prevailed for many years was that of individual cortical cells being ‘feature detectors’ with particular response-criteria. Though not self-proclaimed, Hubel and Wiesel’s theory of a hierarchical visual system employs a form of such feature detectors. I will here discuss: the origins of the feature detection theory; Hubel and Wiesel’s hierarchical theory of visual perception; criticism of the hierarchical nature of the theory; an alternative theory of receptive-field cells as spatial frequency detectors; and the possibility of reconciling these two theories with reference to parallel processing. Barlow (1953) first postulated the existence of feature-sensitive ganglion cells in a frog’s retina based on an inhibitory-surround structure of the receptive field. He maintained that the “on-off” units of these cells triggered by the presence of a particular stimulus corresponded to certain behaviour in the frog. For example, presenting a spot of light in the visual field would cause certain neurons to fire in a particular ganglion cell, and in a live frog, would cause the frog to snap at the stimulus. Barlow concluded that these cells must be “fly detectors”. Lettvin et al. (1959) further examined the visual mechanisms of the frog and discerned fo... ... middle of paper ... ...9). What the frog's eye tells the frog's brain. Institute of Radio Engineer's Proceedings, 47, 1940-1951. Marr, D. (1976). Early processing of visual information. Philosophical Transactions of the Royal Society London Ser. B, 275, 483-524. Martin, K. A. (1994). A brief history of the "feature detector". Cerebral Cortex, 4, 1-7. Sekuler, R. (1974). Spatial vision. Annual Review of Psychology, 25, 195-232. Stone, J. (1972). Morphology and physiology of the geniculocortical synapse in the cat: The question of parallel input to the striate cortex. Investigative Ophthalmology & Visual Science, 11, 338-46. Sullivan, G. D., Georgeson, M. A., & Oatley, K. (1972). Channels for spatial frequency selection and detection of single bars by the human visual system. Vision Research, 12, 383-94. Valois, R. L. (1980). Spatial vision. Annual Review of Psychology, 31, 309-341.
One can almost feel the searing penetration of Lewis Thomas’ analytical eye as it descends the narrow barrel of the microscope and explodes onto a scene of vigorous, animated, interactive little cells—cells inescapably engrossed in relaying messages to one another with every bump and bounce; with every brush of the elbow, lick of the stamp, and click of the mouse…
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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'.
Processing capacity is a very broad and flexible category according to many researchers. In fact, the quote above mentioned suggests that we often fail to notice things that happen just in front of us (unexpected events that are often salient) either because we were completely absorbed by something else or because we had so many things to do at the same time that we couldn’t pay attention to it. We have all at least once failed to see a friend who was waving at us while eating in the cafeteria or walking in a crowded street. The primary question that we should ask ourselves is: how many things can we attend at the same time? The truth is that we didn’t perceive this friend because of a phenomenon called “inattentional blindness”. The problem is that the richness of our visual experience leads us to believe that our visual representation will include and preserve the same amount of detail (Levin et al 2000). In this paper we’ll see the different theories of inattentional blindness, and the classical theories demonstrating this paradigm.
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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...
In response, they proposed that perception is based on the organization of stimuli into holistic and meaningful forms. They are well-known for the phrase "the whole is different than the sum of its parts. " They proposed several "laws" (really heuristics or "rules of thumb") that are referred to as the Gestalt laws of perceptual organization. These are discussed in the module later on.
30 different areas of the brain helps to process color, light, form, and motion to create a single