"Expanding hole" illusion tricks the brain into dilating the pupils

"Expanding hole" illusion tricks the brain into dilating the pupils
The illusion "works" on approximately 86 percent of people who view it
The illusion "works" on approximately 86 percent of people who view it
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The illusion "works" on approximately 86 percent of people who view it
The illusion "works" on approximately 86 percent of people who view it

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

Maybe they could improve this enough to replace dilating drops for eye exams.
Utterly meaningless experiment - of COURSE pupils expand when you concentrate on the dark - that's how pupils work. Fun fact - you can even make things disappear if you stare fixedly at them without moving your eyes - again - how our vision works (we can only see things that move, and our eyes constantly move giving us the illusion that we can see everything). Stare at a fan or dot on the ceiling next time you lie down...
Brian M
Actually the photo of the illusion helps it, I could see the illusion for a second then I realised I was moving the cursor over the image and it zooms in slightly making it look like the dark area is expanding (it actual is and not an illusion!).

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!

Captain Danger
@christopher No meaningless at all. It provides insight in to the way that the eyes work. The actual ambient light does not change but the pupils dilate because the image fools the brain. I am supposed to be working on an electrical schematic at eh moment and my other monitor has a black background with a grid of fine white lines, I can see them just fine , overall it is darker than the image above yet on the image above I loose the ability to determine the edges of the inner black spots as I look at it,
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.
@christopher You are mistaken about spots disappearing if you start at them. The actual cause of that is the blind spot in the retina where the optical nerve attaches. The brain fills in that spot with what it sees around it. If you have the image falling on the blind spot and don't move your eyes away from it, it disappears. The brain does many odd things with vision to help your conscious awareness of your environment seem contiguous.
@Brian M That slight "zooming" effect has been happening on all photos on "New Atlas" for several months at least. I'm not sure what the purpose is, possibly just a subtle way of highlighting the image you're looking at.

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.