Thursday, 11 April 2013

How visual illusions work and how they trick our brain and eyesight

"Most believe that Visual illusions is only something you can have fun with. it is a misconception, ''

"It is important to conduct research into illusions, because they show us how our visual system works. They tell so to speak, what are the basic rules that apply to our Visual apparatus. "

By way of example,  Ramachandran illusion number. 4, where we are forced to react to the shadow. The brain, which is used to light from above in the form of sunlight, assumes that the object is illuminated from above. Turn the drawing 45 degrees-the brain maintains that the objects illuminated from above and therefore creates an entirely new conception of the image.

Illusion 2 shows how the brain is coded to construct an outline based on incomplete data. A useful ability, says Ramachandran, for example this helped our ancestors be able to spot a tiger who sneaks around in some high grass.

Fill in the blind spot
Close the right eye, focus on + sign, and then drag slowly the drawing toward yourself. The red dot will disappear when the focused image in the left retina cover the place where the optic nerve enters out of eyeball-called the blind spot, because it has no photo receptors. But using data from nearby receptors the brain can improvise and fill in the blind spot with oblique lines similar to those that are just around the icing.

Illusory triangles
The white triangle (left) appears to lie on top of the triangle, which is bounded by the blue lines. But if you look long enough, the pages of the white triangle disappears. This is due to the fact that its brightness coincides with the surrounding white color. The illusion works for most, if not blue and Red will appear with straight strong brightness-possibly because the brain cells that can distinguish outlines, might be color blind.

After Pictures
Look at the + sign in the colored circle for 1 minute, and then move your gaze over to the colourless diamond. You will now be able to see areas with colors that complement the original shades. Clockwise from top right, red, blue, yellow and green replacing the original colors. Possible explanation: When neurons, which are susceptible to one color, become exhausted, opposing neurons produce complementary colour.

Shadow provides outline
Since we live in a solbelyst world, we assume that all light coming from above, and therefore we use the shadows to determine the outline and shape. This pattern becomes an X of concave circles when you rotate it 90 degrees to the left. However, if you turn it to the right, it becomes an X of convex circles.

Is there one line?
you may need to be convinced ... but the two featured lines in this corridor are actual equal length. Perspective cheating the brain to perceive the line that is "nearest to", as being shorter. Even though we know that that is what is happening, our Visual apparatus get's confused.

One or two shades of gray?
The color in the two small triangles are the same. They look different to most people, because the yellow and the blue color in the two large triangles affects visual perception. When the brain to pick up colors, it will take the big picture into account.

Faces or vase?
You see either two faces or a vase. But you can not see the faces and the vase at once, because our brain perceives a object by delineating it from its background. Here are both prospects are equally likely, so Visual perception switches back and forth between the two images.

Parallel or not?
The short lines that cross the long, confuses the brain cells, which stands for orienting the perception-and the through-lines are seen therefore as divergent. But that is not the case-try once to turn the drawing, then you see it from the lower left corner ... The long lines are actually parallel.

Where does the grey come from?
There, where the white lines intersect, you can see flashing grey spots. They are due to the way retinal cells respond to light in this geometric image. The contrast between black and white either accelerate or hinder these cell reaction and thus arises the illusion.

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