Scientists have created a flabbergasting optical illusion that makes the viewer feel as if a black hole is getting bigger and is about to engulf them. Whereas in reality, the illusion is just a still image of a black hole surrounded by tiny black dots.
The deceptive image is called the ‘expanding hole’. It was created by Akiyoshi Kitaoka, a psychologist from Ritsumeikan University in Osaka, Japan. Kitaoka further studied the image with a team of researchers at the University of Oslo in Norway and discovered that his illusion could affect the dilation of pupils in human eyes. The researchers tested the expanding hole on 50 subjects falling in the age group of 18-40 years and having normal eyesight.
Interestingly, the illusion worked perfectly even when the size or color scheme of the image was changed during the experiments. “The circular smear or shadow gradient of the central black hole evokes a marked impression of optic flow as if the observer were heading forward into a hole or tunnel,” Professor Kitaoka told The Sun while explaining how a human eye perceives the image.
The researchers presented different versions of the black hole image in front of the test subjects and tracked the movement of their eyes. The pupil (the tiny black circle in the human eye that regulates the amount of light that falls on the eye’s retina) was found to be dilating when the eyes focused on the black hole image. Also, over 86 percent of subjects felt the illusion most captivating when the color scheme was black.
However, when different colors of holes were used, about 20 percent of individuals couldn’t perceive the illusion. Interestingly, when the subjects were shown white-colored holes instead of black, their pupils underwent contraction. Moreover, during the experiments, the researchers didn’t change the external light settings, but the pupil still didn’t react the same way to the different colored images.
These findings suggest that the pupil in our eye reacts to light and explains how we perceive it. Bruno Laeng, the lead author of the study and professor of neuropsychology at the University of Oslo, told IE, “we have learned that the pupillary light reflex is not a closed-loop servomechanism (like a photocell opening a door) which is impervious to any other information that the actual amount of light stimulating the photoreceptors. The eye adjusts to perceived (even imagined) light, not simply to physical energy.”
The expanding hole image makes the eyes feel like the black hole in the image is growing and darkness is increasing in the surrounding. This false perception makes the pupil expand, whereas no light-related change has occurred in reality. According to the researchers, pupil dilation might also be a result of our brain predicting a future image as “an illusory expansion” of the large black hole region in the original image.
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