The mechanisms of optical illusions have been a point of interest for many people in the globe. Recently, there are numerous examples of such images that trick the mind and leave people puzzled.
Here is an image which has gone viral recently and is apparently unique, because only 1% of people can find the animal in it.
The so-called McCollough effect is a trick on the mind, which occurs after staring at a colored grating (alternating lines) for several minutes. This effect makes your brain start to see a pinkish tinge or other colors when you are looking at black-and-white lines.
By tilting the head 90 degrees, you may improve or reduce the effect, and by rotating the induction images you can reverse it. Also, when you look longer at the original induction images, the effect will last longer, too.
A visual illusion is the name of this phenomenon, which is actually the retinal impression that persists after the removal of a stimulus, and exists as a sort of afterimage. According to the researchers, it is a result of the continued activation of the visual system.
The experts found that the strong colors make an impression on the visual system and trick it into thinking that it is still looking at the colors even when it is not. This visual effect eventually makes you believe that what you see are black and white stripes, which are tinged with red and green.
According to the Journal of Experimental Psychology, this effect can last for over three months in case the perceiver looks at the colorful gratings for extended periods of time in the same way as the bright flash of the camera can linger in the vision.
The name of this effect is given after the discoverer, US psychologist Celeste McCollough Howard. He found this so-called “contingent aftereffect”, which is an illusion that affects your brain for an extended period of time.
Many studies were conducted to prove this effect, and back in 1975, were tested five groups of 16 people. One of the groups showed that the effect didn’t decrease even after five days, and it remained better than half strength for four groups up to 2,040 hours later (almost three months).
Everyone can test it for himself with the images below, and that test is harmless and can affect his vision for a while.
The cause of these effects became very important for the researchers, who are trying to identify it, believing that they are linked to the neurons in the visual cortex. Other researchers think that the brain tries to color-correct the world and gets a bit stuck. For the third group, this is a kind of withdrawal symptom, which is caused by the absence of color.
In the examination in 1995, researchers found that the patient who has suffered significant brain damage, looking at the red-and-green gratings still reported that the effect worked when using a black-and-white grating. This finding helps the researchers to conclude that the effect was probably occurring within the visual cortex, or on the way between the eye and the brain.
This belief is also confirmed by Julien Ciroux, claiming that the processing mechanisms involved in the ME [McCollough effect] are located in the primary visual cortex.
If you look at those two induction images you can stimulate the effect, alternating between staring at their centers for a few minutes. Looking at this image afterward, you will see it green or red in parts or even pinkish.
The results of the study in 1969 showed that various stripes colored red and green produced the after-effects and if the induction image was green, it was seen as with red colors on vertical grates and green colors on horizontal grates afterward.
The red induction image was seen with those colors reversed. The researchers concluded that only green and red produced the effect.
Experts believe that grating is linked to neurons in the visual cortex responding more strongly to their spatial frequency and preferred orientation.
According to the researchers, if you don’t see the effect after a few minutes of looking back and forth, you shouldn’t continue to do it for longer.