Visual information is seen because light passes through the cornea and is focused by the lens as an inverted image on the retina (Ellis, 2004). The retina is composed of photoreceptor cells; rods and cones with the greatest density of cones situated within the fovea, thus vision is sharpest for images and information projected to the fovea (Ellis, 2004). Subsequently visual information of lateralized foveal stimuli projects to the cerebral hemisphere within the brain. In the brain, the left visual hemifield projects to the right hemisphere and the right visual hemifield projects to the left hemisphere (Lavidor, Ellis, Shillcock & Bland, 2001). Generally for most individuals (in particular right handed), visual recognition of words and information is more efficient for display within the right visual field. However it is debated whether foveal information lateralized within the left or right visual field is double-projected to both hemispheres or unilaterally projected to the contralateral hemisphere because the fovea is anatomically split and there is differential contribution of the two hemiretinae.
Two theories have been put forward regarding how visual information is projected to the hemispheres. According to the split fovea theory, hemispheric division in processes occurs right up to the point of fixation. When the eyes are fixated within a written word visual information about the letters falling to the left of fixation initially projects to the right cerebral hemisphere, whilst visual information about the letters falling to the right of fixation project to the left cerebral hemisphere. Foveal processing is split so precisely at the vertical midline that all letters at either side of fixation project (unilaterally) to th...
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...occurring in foveal vision away from the midline however this is not visible or obvious when recognition of visual information occurs. There is an overlap at the centre of the fovea where information projects simultaneously to both hemispheres, this being consistent with the bilateral theory. On the other hand, split fovea theory is an interesting theory of fixation effects that has been inspired by previous research unconnected with split fovea theory and thus incapable of providing appropriate evidence. More recently, split fovea theory has been based on experiments conducted specifically in its support but in which fixation locations were not monitored and stimuli exceeded foveal vision. It is good to see that research in the area is beginning to improve but it is difficult to be enthusiastic about any theory when there is no compelling evidence to support it.
Hubel and Wiesel’s research surrounding area V1 of the primary visual cortex provided one of the first descriptions of the receptive fields in mammals. By flashing various lines along the receptive field, Hubel and Wiesel were able to classify cortical neurons into two distinct groups; simple and complex (Hubel & Wiesel, 1963). The use of manually mapping the receptive fields with simple dots, lines and edges meant that they not only discovered orientation tuning in single neurons, but also described the columnar organisation of ocular dominance and orientation preferences in the cerebral cortex (Ringach, 2004). Although Hubel and Wiesel’s findings were an extreme advance in our understanding of the visual cortex (Wurtz, 2009), it became apparent that there were cells in the visual system that responded to stimuli far more complicated than orientated lines meaning that the cells in area V1 were much more modifiable than Hubel and Wiesel had suggested. In this essay, Hubel and Wiesel’s classic receptive field shall be discussed along with reasons as to why it can no longer offer us a satisfactory explanation into visual perception. First to be discussed are the specific types of cells which were defined in Hubel and Wiesel’s classic experiment into the striate cortex.
The braine is part of three divided that represent front, back and saggital planes which divides the left from right of braine. A horisontal planes divides the braine in to top and bottom position.
Witelson SF (1995) Neuroanatomical bases of hemispheric functional specialization in the human brain: Possible developmental factors. In Kitterle FL (Ed), Hemispheric communications: Mechanisms and Models. (pp. 61-84) New Jersey: Lawrence Erlbaum Associated, Inc., Publishers.
Against a bleak backdrop, U.S troops stand thrusting an American flag into the grey skies. The shards of wreckage at their feet speak of the arduous journey these soldiers had taken to reach the summit of the mountain. Despite the grim setting on the ground, the American flag waves on in a perfect manner swaying along with the wind gusts. As a photograph taken by Joe Rosenthal in 1945, this image of U.S troops raising a flag in Iwo Jima during World War II served as a symbol of hope and victory for the American public during the gruesome end to war. The photograph earned Rosenthal a Pulitzer Prize, and showed the extant of the power of a photograph to elicit emotion from an audience. These emotions have the ability to affect ones’ perception towards what the photograph is depicting. However, if these photographs can produce an emotional response, is it possible for them to steer the perception of the audience in a desired direction? If so, is there a way for one to sift through the possible propaganda?
The left brain or the left cerebral hemisphere is the side of the brain that is logical. It controls speech, language and analyzes all incoming information Cherry (2013). These patients has the ability to recognize people names rather than faces Cherry (2013). The left hemisphere usually has preemptive control over the main stream of the body activity (Newman, Banks, & Baars (2003 pg. 838)). The Left cerebral hemisphere is superior to complex language and expres...
The cerebrum consists of two hemispheres, separated by a deep fissure called the Corpus Callosum, the hemispheres are divided into four lobes; the frontal, partials, occipital and temporal.
The high percentages of individuals who endure this impairment justifies and practically demands future research because the causes are not fully understood. The need for future research can be better emphasized if those with normal vision try to empathize with victims of macular degeneration. One can only imagine how frustrating it must be to receive sensatrions only in the periphery of the retina. Because the macula encompassed the cone rich fovea, which is used to focus on objects, the fovea degenerates as well. This occurence inables individuals to interpret the sensations they experience. Reading, ...
The changes occurred in the outer layer of the brain. Precisely, the cortex changed. The deeper structure of the brain was influence by the change specially the thalamus. This organ of the brain filters the visual information. The thalamus sends the visual information to the virtual cortex. The coordination between the two organs of the brain helped the performance of the reading by the Indian
hemispheres of the brain in which he stated that " . . . left - hemisphere style
The corpus callosum binds the left and right hemispheres of the brain together, both physically and communicatively. After this operation has been performed, there was a remarkable development with how we perceive things and some of the results showed how much we rely on the connection between the two halves of our brain. There are also advantages of having a split brain. A study performed by Rogers et al, 2004 found that when you have two halves of a brain then it increases your ability to both look for food and watch for predators at the same time. Possibly demonstrating that the connections between our ancestors’ brain hemispheres were less developed. Another advantage is having the ability to read two pages at once. Of course, there are more disadvantages than advantages of having a split brain. An example of one is the most famous split brain study of all time, Sperry, 1968. In this study each participant, all having two halves of a brain, was shown two different images. One in each visual field and when asked to draw the image they had just seen they would draw the image they saw on the left but they would describe it as the image they saw on the right. This shows that the left side of the brain, which controls the right visual field, contains the information to be able to describe an object when seen
The 'Secondary' of the 'Secondary'. A physiological correlate of the “zoom lens” of visual attention. The Journal of Neuroscience, 23(9): 3561-3565. Shinn-Cunningham, B. G. (2008). Object-based auditory and visual attention.
Nowadays, it is widely known that the right and left hemisphere have different functions. The two hemispheres are equally important in a daily life basis. Nevertheless, in the 1960’s this was not common knowledge. Even though today the importance of the brain hemispheres is common knowledge, people don’t usually know to whom attribute this findings. One of the people who contributed to form a more defined picture about the brain hemispheres and their respective functions was Roger Wolcott Sperry, with the split brain research. Roger Sperry did more contributions than the split brain research, but this is his most important and revolutionary research in the psychological field. Thanks to the split brain research, Sperry proved that the two hemispheres of the brain are important, they work together and whatever side of the brain is more capable of doing the task is the hemisphere that takes the lead.
Perception is a mysterious thing; it faces a lot of misconception, for it can merely be described as a lens, as it decides how someone views the events happening around them. Perception is the definition of how someone decides to use their senses to observe and make conceptions about events or conditions they see or that are around them. Perception also represents how people choose to observe regardless if it’s in a negative or positive way. In other words, perception can be described as people's cognitive function of how they interpret abstract situations or conjunctures around them. All in all, perception can do three things for someone: perception can change the way someone thinks in terms of their emotions and motivations, perception acts
The right side of the brain is good at imaginative and expressive acts. Its work is to process information for instance recognizing faces, reading emotions, expressing emotions, images, color, and creativity, just to mention but a few (Cherry, 2012). Right brain thinkers retain more information from visual experiences. On the other hand, the left side of the brain has a number of functions, which involve language, logic, and analytical thinking. The left side of the brain processes information such as; language, logic, reasoning, numbers, and critical thinking (Cherry 2012). These brain functions affect the left side of the brain, and decision-making. Both sides of the brains enhance the learning and thinking process as the brains incorporated their functions. Both sides of the brain participate in a balanced manner during the lear...
Visual perception and visual sensation are both interactive processes, although there is a significant difference between the two processes. Sensation is defined as the stimulation of sense organs Visual sensation is a physiological process which means that it is the same for everyone. We absorb energy such as electro magnetic energy (light) or sound waves by sensory organs such as eyes. This energy is then transduced into electro chemical energy by the cones and rods (receptor cells) in the retina. There are four main stages of sensation. Sensation involves detection of stimuli incoming from the surrounding world, registering of the stimulus by the receptor cells, transduction or changing of the stimulus energy to an electric nerve impulse, and then finally the transmission of that electrical impulse into the brain. Our brain then perceives what the information is. Hence perception is defined as the selection, organisation and interpretation of that sensory input.