Let it never be said that I do not suffer for my art. In bringing this article to you, I have sustained quite a severe headache. It might also have something to do with the fact I've just downed two bottles of coke (it there's free coke, I'm going to drink it), but it's probably got more to do with this rather bizarre image which actually affects your brain.
The image itself is rather innocuous, however it is responsible for a sensory phenomenon which is still yet to be fully understood. Sensory illusions are nothing new, we've all seen spinning GIFs and magic eyes, but the difference with this image is that it is long lasting. Usually, excessive blinking or rubbing your knuckles into your eyes is enough to reverse any of these illusionary effects, but that doesn't work with this one.
Called the McCollough Effect, it is unique partly because it is so long lasting. This means its cause has less to do with manipulating how the eyes see, but perhaps how the brain interprets information.
At this point, I should stress a disclaimer. The visionary alteration caused by the McCollough Effect - if induced correctly - usually lasts over an hour, however in some cases it has been known to continue for three months. With this in mind, you have been warned and you continue at your own peril. Don't sue me please.
What is the McCollough Effect?
The McCollough Effect, which was discovered by American psychologist Celeste McCollough in 1965, involves a set of images containing both horizontal and vertical grills.
The idea relies on making the brain appear to see color where there is actually none. To do this, you need to induce the effect in your brain.
Step 1: Stare at the test image
Firstly, you must stare at the below test image for up to a minute.
Step 2: Stare at the colored induction images.
After this, you must stare alternatively at the two images below. It is important you stare at one for several seconds (ideally in the center) and before changing to the other and repeating the process. Alternate between the two for periods of several seconds for up to three minutes.
Step 3: Look at the test image again
Now look back at the test image. Although it was (and, indeed, is) black and white, it should not appear as having a light green and pinkish hue.
So did it work for you? The effect might be very subtle, or rather marked, depending how long you stared at both the test and colored images.
What Have I Just Done To My Brain? How Does The McCollough Effect Work?
There reason for the McCollough Effect is still relatively open to debate. Some suggest it is caused by changes to the neurons in the eyes, while others suggest something deeper is occurring. Generally, there are three different, but related, explanations:
1. McCollough's personal explanation is that staring at the inducement images somehow adapts the edge sensitive neurons in the lower, monocular regions of the visual cortex. Now, I'm no expert, but what I understand this to mean, is that the part of the eye which is designed to recognize straight edges have been altered to now see color next to all examples of straight edges.
2. Another explanation is that this is the visual cortexes 'error-correcting device', which is designed to maintain an accurate internal representation of the external world. The images you stared at are extremely rare - or indeed impossible - in the natural world. This means the consistent staring at the two inducement images may result in some kind of 'pathology' in the eye. Therefore, the 'error-correcting device', on recognizing the straight lines of the test image, may attempt to compensate for their lack of color by adjusting the appropriate neurons to a similar state as when you were looking at the colored inducement images.
3. A third explanation suggests the phenomenon may be related to some kind of classical conditioning in the brain. In this sense, the McCollough Effect is explained by the same principles as pharmacological withdrawal symptoms, although clearly on a much less severe scale. This is where it gets pretty complex, but from what I understand, the straight lines are akin to the 'drug'. When the brain recognizes them, it re-introduces the colors which were present when the lines were first introduced to it. Because of the manner of staring at them, and their opposite colors, the brain now associates straight lines as featuring green, and horizontal lines as featuring red.
Did It Work For You?
In the interest of public safety, I tested the McCollough Effect and I can confirm it does work. Indeed, I stared at the images about 45 minutes ago, and still I can see it. Admittedly, the effect is rather subtle and kind of gave me a headache, but it also rather interesting to know my brain is doing something - whatever it is - behind the scenes that I can't control.