Social media is on its knees once again before a curious optical illusion. At first glance, we can recognize the face of a woman with inverted colors, and a small white dot on her nose. The suggestion is to stare at that dot for 15 seconds, and when we move our gaze aside, the woman's face appears even with a hint of color. It's clear that the eyes-nerves-brain combination is having fun with us, but what exactly is happening?
The development of the illusion itself is not at all strange. In fact, we can make an exact replica by taking any photo, inverting its colors with an image editor (Paint.NET, GIMP, Photoshop, etc.), and adding a dot in the center as a reference. But there are times when the Web manages to surprise itself. Perhaps the success of this particular optical illusion is related to the source, the always controversial and extraordinarily popular Daily Mail. The mechanics of social networks did the rest, and the image appeared almost everywhere, which reminds us a bit of that damn dress that my brain and my sense of sight insist on interpreting as white and gold. All the user has to do is look at the white dot on the woman's nose for 15-20 seconds without blinking, and then look at the light section next to it.
Well, personally, I can see the woman, which leads me to the next question: Is there something wrong with my eyes? Actually, no. Dr. Juno Kim of the School of Optometry and Vision Science at the University of New South Wales explained to the Daily Mail that it's a so-called "negative afterimage". Information going from the back of the eye to the brain is transmitted through three opposing neural channels (white and black with grayscale, green and red, blue and yellow). If we observe something with a specific color for a prolonged time, the cells sensitive to that color are stimulated, activating the corresponding channel. The activity of the cells reaches a peak, then gives way to a state of fatigue and decline. If we then shift our gaze to a uniform background, the decline deepens further, causing the opposite color to become stronger. That's what allows us to see a trace of color in the illusion.
As I mentioned above, from this you can create your own optical illusions with all kinds of images. The effect will be different in each case, but if you can induce enough fatigue, it should manifest itself without problems.
Daily Mail
