When you view the image above, does it look like black smear in the center is expanding? If it does, that means you're like most people – and your brain may even think that you're entering a tunnel, adjusting your eyes accordingly.
As part of a recent study led by the University of Oslo's Prof. Bruno Laeng, a total of 50 adult test subjects with normal vision (31 female, 19 male) were asked to look at the newly developed "expanding hole" optical illusion.
They viewed 26 versions of it, in different smear/dots color combinations. The simple combo shown here – with a black smear and dots on a white background – produced the strongest reaction, with about 86 percent of the participants reporting a perception that the hole was expanding.
What's more, it was found that the greater the reported perception, the more the person's pupils unconsciously dilated as they viewed the illusion. This suggests that their brains were reacting as if the individuals were actually entering a dark tunnel, opening their pupils wider in order to take in more light.
"Here we show based on the new 'expanding hole' illusion that that the pupil reacts to how we perceive light – even if this 'light' is imaginary like in the illusion – and not just to the amount of light energy that actually enters the eye," said Laeng. "The illusion of the expanding hole prompts a corresponding dilation of the pupil, as it would happen if darkness really increased."
It is now hoped that these findings could lead to a better understanding of the ways in which our visual system makes sense of the world around us.
A paper on the research – which also included Prof. Akiyoshi Kitaoka from Japan's Ritsumeikan University, and doctoral student Shoaib Nabil from Britain's University of Sussex – was recently published in the journal Frontiers in Human Neuroscience.
Source: Frontiers
Viewing it with Edge, tried it under Chrome and it does zoom in with cursor, but the illusion of dark center spreading out doesn't seem to work now, guess once you know something is an illusion your brain adjusts to cancel it or at least with me!
If your statement was correct as soon as I looked at something that was mostly dark I would not be able to see contrasting object as I stared at it.
I've always been fascinated with optical illusions and the way the brain reacts and adjusts to changing visual cues. When I was a senior in high school in 1969, the physics department conducted an experiment with several students that didn't need corrective lenses. They were given glasses that inverted everything they observed. The first day of the experiment, the subjects had to walk very carefully, stopping frequently to orient themselves and the rest of us stayed out of their way. When they returned to school the second day after wearing them at home the evening of the first, their brains began correcting for the inversion and their navigation was much improved. By the third day all of the group were back to near normal visual perception.