Three Planks or Four?
Optical illusions play on the translation between what your eye sees and what your brain perceives. Optical illusions use color, light, and patterns in to mislead our brains. But if you take your time and look closely you’ll figure out how it’s tricking you into seeing something you’re not.
Look at the plus sign in the middle of the circle. As you stare (it may take 20 seconds or so), the lilac dots fade to gray. The rotating dot that’s traveling around the circle appears to become a rotating dot of green.
Why Do We See In Color?
The blank dot turns green because your retina is being oversaturated with the lilac colored dots. When the lilac is removed from the spots, you see green, the opposite color on the color wheel.
The Müller-Lyer effect is one of the best known geometric illusions. The lines appear to be different lengths as the arrowheads point in or out.
For most people the line with the arrowhead pointing outward looks longer and the arrowhead pointing inward looks shorter, when in reality each line is the same length.
It all has to do with cues the brain picks up about depth. When the arrowhead is pointing inward, we perceive it as sloping away. This depth cue leads us to see the line as further away and therefore shorter.
When the arrowhead is pointing away from the line, it looks more like the corner of a room sloping toward the viewer. This depth cue leads us to believe that this line is closer and therefore longer.
This illusion was discovered in 1973 by researcher Richard Gregory. When the tiles are misaligned, the lines appear to slant, giving the rows a wedge appearance. But the lines are actually parallel and all tiles are of the same size. When the tiles align, or make up a checkerboard, the illusion disappears. This has to do with the way the retina processes the light spread from dark to bright zones that are next to each other.
Which do you see? Can you see the face when tilted or do you see a word when it’s horizontal? This is called a double meaning optical illusion. The orientation of the scribble gives it context. If you look closely the white line turns into a word (which becomes more obvious and easier to read if you try tilting your head slightly to the right). What does the four letter word say? Don’t worry; you can be honest.
The scintillating grid illusion is an optical illusion discovered in 1994. The dots seem to appear and disappear at random intersections, which is why it’s called “scintillating.” When you look directly on a single intersection, the dark dot does not appear. Theories on why this happens are conflicting. But while you see dark dots in the periphery, you can chase them all day long and won’t be able to look directly at them.
Can you see the movement? The rotating snake illusion makes you see motion that isn’t happening. Focus on the illusion using your peripheral vision and you’ll notice circles spinning in the opposite direction. If you stare directly at the image the motion may decrease. Why this illusion causes you to see motion is still yet to be determined. So far we know the arrangements of the edges activate the neurons in your brain.
These mind boggling images are fun for everyone. Let your family and friends be baffled by the illusions today. Share on your Facebook and/or Twitter.
And don’t forget, as complex as these neurological responses are, you want to make sure your retina is always in tip-top shape, so get a regular eye exam from a VSP eye doctor.