A recent study by scientists from the University of Oslo in Norway and the University of Ritsumeikan in Japan showed that the human eye adapts better to optical illusions than we thought so far. The new type of illusion developed by them can affect our brain to such an extent that just looking at it causes the pupil to react.
Most of us have come across optical illusions – images that trick our brains. Parallel lines that appear curved, perspective distorting distances, or seemingly moving objects – many of these illusions take advantage of the properties of our eyes. Recent research has shown that the eyes react to certain delusions in unexpectedly complex ways.
Journey to the interior of a black hole
The subject of the research were static images with a black, white or colored central element placed on a light or dark background. The graphics have been designed in such a way as to give the impression of “expanding” upon closer inspection. Contrary to classic static optical illusions, this type of illusion has not been known to science until now.
The images were presented to 50 volunteers with good eyesight. The researchers recorded the participants’ reaction to each image by measuring the degree of pupil dilation before and after presenting the specific image. Volunteers were also asked to rate the speed and degree of “spread” of the illusion.
Analysis of the results indicated that most participants’ eyes were clearly responsive to the optical illusion. The biggest changes were caused by the black points. The authors say that their apparent movement gave subjects the impression of “traveling inside the black hole”, causing the pupils to dilate. The brain reacted completely differently to white and colored points on a dark background, the “spreading” of which caused the pupils to narrow slightly, as if a faint light shone into the eyes of the participants.
Everything is a matter of perception
As the researchers point out, most of the study participants were able to observe the illusion. 86 percent of volunteers recorded apparent movement in the image with a black element, and 70 percent – in the color graphics. In the case of “black holes”, the researchers noticed another regularity: the more participants thought the illusion “dilated”, the more the diameter of their pupils changed.
According to Bruno Laeng, the study’s lead author, the results ‘shed new light’ on how vision works.
– The eye adapts not only to the physical energy of light, but also to how we perceive or imagine light – says the scientist.
The researchers emphasize that future research into optical illusions may reveal further types of physiological changes that will allow us to understand how optical illusions work.
Frontiers in Human Neuroscience
Main photo source: twitter.com/AkiyoshiKitaoka