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(Animated Gifographic) Optical Illusions, How Our Eyes Trick Our Mind

Optical usions How our Eyes rick Your Mind "We tend to regard what we see as the real world. A lot of it is distortion, and it is occurring in the early processing of the brain, before consciousness takes over. The cells of the primary visual cortex create small distortions, which then pass on to the higher levels of the brain, to interpret best it can. These illusions happen very fast. Even the higher brain cannot always correct for them, as it doesn't in fact know they are illusions." -Dr Isabelle Mareschal, Researcher, University of Sydney* Vision Os Mind Over 50% of the cortex, the large outer layer of the brain, is devoted to vision. Optical illusions illustrate that the mind Vision is the most complex sense. makes assumptions about the world. Optical Illusions reveal how the mind processes time and space, to how it experiences consciousness. What a person thinks they see is often not the truth. Optical lusions Origins, The Ancient Greeks Illusions can be traced back to the Ancient Greeks. In 350BC, Aristotle made reference to an effect called 'motion aftereffect' or the 'waterfall illusion'. Watch a waterfall. Shift your gaze to the static rocks below it. The rocks appear to move in the opposite direction to the water flow. Tracking water flow temporarily affects certain neurons in the brain as they adapt to identifying motion. When your gaze is shifted to the rock, competing neurons overcompensate which causes the illusion of movement in the opposite direction. 19th Century lusions Primitive Perceptions 1 Ohe Ebbinghaus Musion Our brain makes judgements about size using adjacent objects. This can be manipulated. The orange circles in the illusion are actually the same size. The Ponzo llusion Context is fundamental for depth perception. Identically sized lines can appear to be different lengths when placed between converging parallel lines. The slanted lines make us believe the top line is further away. The brain gets confused and it overcompensates, making the top line appear bigger. (3 The Muller-Tyer Musion The lines appear to be different lengths. The arrows at each end trick the brain into thinking the lines are nearer or further away and that it is looking at a 3D scene. The brain overcompensates, making the arrows on the middle line appear longer than the other lines. The Helmholtz llusion4 A simple square of vertical lines appears shorter and wider than a square of horizontal lines. There isn't always an explanation. It is believed that it is to do with how the brain estimates "filled space". 20th Century llusions, Scientists Os Artists Scientists Artists David Hubel and Torsten Wiesel discovered that certain neurons in the brain's visual Illusions in the 1960/70s inspired an artistic style called "Optical Art'. cortex fired only when objects were orientated at certain angles. Victor Vasarely is the father of this movement. For example, specific neurons fire when you look at a square and a triangle. His work is still studied by scientists today. The finding earned them a Nobel Prize in 1981 in the area of perception. Research using his 'Nested Squares Illusion' suggests that the brain identifies shapes using corners instead of lines. 21st Century lusions Theoretical Neurobiology Resurgence in Mlusion Research The brain constantly tries to predict the future to compensate for the slight delay between an event and our conscious perception of it. A whole class of classic 'coffee-table' geometrical illusions fit with this theory, according to Mark Changizi, a theoretical neurobiologist. Classic 'Coffee Jable' Musions The Hering lusion Features radial lines that give the illusion of movement. Our brain has evolved to treat these radial lines as if they are in motion. This is a misinterpretation by the brain. The Necker Cube llusion A brain-imaging study of people looking at this illusion revealed that the brain can flip between two different views. The brain attempts to translate a 2D drawing on a page into a 3D cube. The brain is tricked into perceiving the cube as a 3D object. The Hermann Grid llusion The brain sees grey dots in the intersections between the white and black grid. If you look directly at one of the grey dots it disappears. Brain-scanning research tells us that our neurons are competing with each other to see the light and dark parts of the image. Yet it cannot account for the fact that the effect changes when the grid has curved lines instead of straight ones. The Reality of Optical llusions Our visual system remains too limited to tackle all of the information our eyes see. Our brain would need to be much bigger to process this. Our brain takes shortcuts and chooses the most likely interpretation of what it thinks our eyes see. Seeing is not always believing. "This expert is in no way affiliated with Supersavers Opticians. References Supersavers Opticians Qualified Opticians Serving The Public

(Animated Gifographic) Optical Illusions, How Our Eyes Trick Our Mind

shared by Jon123 on Jul 05
This animated Gifographic called ‘Optical Illusions, How Our Eyes Trick Our Mind’ tells about - .Over 50% of the cortex, the large outer layer of the brain, is devoted to vision. .Optical illusi...


Jon Munro




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