Ludimar Hermann first observed the Hermann grid and characterized it by “ghostly gray spots seen at the intersections of a white grid on a black background” (Spillmann & Levine, 1971). Baumgartner believed that this effect was due to inhibitory processes in retinal ganglion cells, the neurons that transmit signals from the eye to the brain (Baumgartner 1960). However, the Hermann Grid alone only provides a biological explanation of visual processing and so, to attempt to fully explain visual processing, we must look for explanations that also include the environment in the explanation. Say no to plagiarism. Get a tailor-made essay on “Why Violent Video Games Should Not Be Banned”? Get an original essay At the center of an intersection, there is more light in its inhibitory environment than the receptive field elsewhere along the same line. More light in the inhibitory environment means there is more lateral inhibition at the intersection. Lateral inhibition disables the propagation of action potentials from excited neurons to neighboring neurons in the lateral direction (Yantis and Steven, 2014). This creates a contrast in stimulation that allows for heightened sensory perception. An important feature of the Hermann grid is that when looking directly at the intersection, no gray spots will appear but rather see them in peripheral vision. This is because the receptive fields in the central fovea are much smaller than in the rest of the retina and are too small to span the width of an intersection. Conversely, Hermann's grid provides only a limited explanation of visual processing. Schiller and Tehovnik (2015) cite three main flaws. First, although our receptive fields remain the same size, when the Hermann grid changes size, the illusion changes in the same way. Second, the illusory effect can be greatly diminished, or even eliminated entirely, by tilting or distorting the grid, even by just 45 degrees. Third, the actual arrangement of retinal ganglion cells and their corresponding receptive fields is not as simple as Baumgartner supposed. Midget and Parasol ganglion cells exist in different proportions throughout the retina, with the latter having much larger center-surround receptive fields than the former. This complex arrangement of excitatory centers and inhibitory environments, operating at different distances on the 2D retinal image, means that localized Baumgartner retinal processes cannot explain the Hermann grid effect (Schiller and Carvey 2005). Therefore, it can be concluded that visual processing cannot be explained solely by lateral inhibition, and therefore there must be alternative explanations. Cognitive explanations suggest that we process visual information through cognitive processes such as attention and retention. The two main cognitive explanations of visual processing include the work of James Gibson and Richard Gregory. James Gibson's bottom-up theory suggests that perception involves innate mechanisms forged by evolution and that no learning is required. This suggests that perception is necessary for survival because without perception the environment would be very dangerous. Our ancestors would have needed perception to escape harmful predators and to know which fruits are poisonous and which are safe to eat, suggesting that perception is evolutionary. The starting point of Gibson's theory was that the pattern of light reaching the eye, known as the optical network, contains all the information.

Essay / Ludimar Hermann first observed the Hermann grid and characterized it by “ghostly gray spots seen at the intersections of a white grid on a black background” (Spillmann & Levine, 1971). Baumgartner believed that this effect was due to inhibitory processes in retinal ganglion cells, the neurons that transmit signals from the eye to the brain (Baumgartner 1960). However, the Hermann Grid alone only provides a biological explanation of visual processing and so, to attempt to fully explain visual processing, we must look for explanations that also include the environment in the explanation. Say no to plagiarism. Get a tailor-made essay on “Why Violent Video Games Should Not Be Banned”? Get an original essay At the center of an intersection, there is more light in its inhibitory environment than the receptive field elsewhere along the same line. More light in the inhibitory environment means there is more lateral inhibition at the intersection. Lateral inhibition disables the propagation of action potentials from excited neurons to neighboring neurons in the lateral direction (Yantis and Steven, 2014). This creates a contrast in stimulation that allows for heightened sensory perception. An important feature of the Hermann grid is that when looking directly at the intersection, no gray spots will appear but rather see them in peripheral vision. This is because the receptive fields in the central fovea are much smaller than in the rest of the retina and are too small to span the width of an intersection. Conversely, Hermann's grid provides only a limited explanation of visual processing. Schiller and Tehovnik (2015) cite three main flaws. First, although our receptive fields remain the same size, when the Hermann grid changes size, the illusion changes in the same way. Second, the illusory effect can be greatly diminished, or even eliminated entirely, by tilting or distorting the grid, even by just 45 degrees. Third, the actual arrangement of retinal ganglion cells and their corresponding receptive fields is not as simple as Baumgartner supposed. Midget and Parasol ganglion cells exist in different proportions throughout the retina, with the latter having much larger center-surround receptive fields than the former. This complex arrangement of excitatory centers and inhibitory environments, operating at different distances on the 2D retinal image, means that localized Baumgartner retinal processes cannot explain the Hermann grid effect (Schiller and Carvey 2005). Therefore, it can be concluded that visual processing cannot be explained solely by lateral inhibition, and therefore there must be alternative explanations. Cognitive explanations suggest that we process visual information through cognitive processes such as attention and retention. The two main cognitive explanations of visual processing include the work of James Gibson and Richard Gregory. James Gibson's bottom-up theory suggests that perception involves innate mechanisms forged by evolution and that no learning is required. This suggests that perception is necessary for survival because without perception the environment would be very dangerous. Our ancestors would have needed perception to escape harmful predators and to know which fruits are poisonous and which are safe to eat, suggesting that perception is evolutionary. The starting point of Gibson's theory was that the pattern of light reaching the eye, known as the optical network, contains all the information.

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