A new optical illusion can deceive most of us into perceiving expansion black holenew research reports.
The picture is completely still, but researchers money it gives people a “growing sense of darkness, as if entering a space emptied of light.”
The illusory forward motion is probably the way our mind prepares us for a change of scenery. By predicting a change from brightness to darkness, our visual system can adapt much more quickly to potentially dangerous conditions, the researchers suggest.
“Just as brightness can be blinding, being plunged into darkness is probably risky when navigating in the darkened environment,” the authors note. write in their new paper.
“Although, as in any illusion, this virtual expanding darkness is being experienced at the expense of verdictsince the observer neither advances nor enters any dark space, such a cost is likely to be less severe than if there were no corrections when an observer actually advanced into dark space. “
The first study to analyze this optical illusion explored how the color of the hole and the surrounding points affect our mental and physiological responses.
To do this, a group of 50 participants with normal vision were presented with ‘expanding hole’ images of various colors on screen. In the series, they were also shown mixed versions of the illusion with no visible pattern in light or color.
The illusion of forward motion was most effective when the hole was black. When the hole was in this shade, 86 percent of participants felt as if the darkness was heading toward them.
Tracking the participants’ eye movements revealed that their pupils were unconsciously dilated at the sight of the black hole.
Meanwhile, if the hole was white, their pupils only slightly contracted.
“Here we show on the basis of the new ‘expanding hole’ illusion that this learner reacts to how we perceive light – even if this ‘light’ is imaginary as in the illusion – and not just to the amount of light energy that actually enters the light. eye, ” says psychologist Bruno Laeng from the University of Oslo in Norway.
“The illusion of the expanding hole prompts a corresponding dilation of the pupil, as would happen if darkness really increased.”
The authors are not sure why 14 percent of the group did not perceive any illusory expansion when the hole was black. But even among those who did perceive the illusion, the force of feeling varied.
The people who felt the illusion the strongest were also those whose pupil diameters had changed the most.
“Our results show that the dilation or contraction reflex of pupils is not a closed-loop mechanism, like a photocell opening a door, impenetrable to any information other than the actual amount of light stimulating the photoreceptor.” says Laeng.
“Rather, the eye adapts to perceived and even imagined light, not simply to physical energy.”
The authors have a hypothesis as to why the eye can do this. When the central region is black, our students are likely to prepare us for a change of brightness in the near future.
Instead of seeing the information that is presented directly to us, the visual neural network predicts how that information will change in the future, generating “illusory “outer expansion” of the central “hole” region“.
If the brain did not do this, the new visual information would take milliseconds longer to reach higher processes in the brain. If our pupils needed so long to dilate, we might not be able to navigate the darkness so effectively.
The authors now want to test whether other animals are also deceived by the illusion to better understand how the human visual system has evolved.
The study was published in Limits in Human Neuroscience.