In the 2000 science fiction film field black (now streaming on Peacock!), prisoner Richard B. Riddick, is escorted onto a small spaceship which crashes on an alien planet. Despite three suns in the sky, a rare eclipse plunges the planet into total darkness and the crash survivors find themselves at the mercy of a predatory alien species. Luckily, Riddick has surgically modified eyes that allow him to see clearly in the dark. If you’re going to find yourself in a lightless world with ravenous monsters, it helps to have a super-powered Vin Diesel in your corner.
Here on Earth, we also have a kind of superpower when it comes to seeing in the dark. The pupils of our eyes are able to open and close as needed, depending on the amount of light we perceive. We can, quite literally, adjust our vision to match our surroundings. At least, that’s how we feel about what’s going on.
A new illusion consisting of a dark central hole surrounded by a gradient on a field – pictured above – presents evidence that our eyes don’t actually react to the light in our surroundings. Bruno Laeng from the Department of Psychology at the University of Oslo and his colleagues studied the new illusion devised by co-author Akyoshi Kitaoka. They found that looking at it caused most people’s pupils to dilate, as if they were entering a darker environment. Their findings were published in the journal Frontiers of Human Neuroscience.
Laeng, the study’s lead author, previously studied another illusion created by Kitaoka that featured what appeared to be bright light emerging from a gradient. Despite the fact that the center of this illusion is the same color and brightness as the background, its position in the gradient makes it look and feel almost painfully bright.
“It led me to investigate the possibility that our eyes actually adjust to illusions, not reality, but what we think reality is or is about to be,” Laeng told SYFY. WIRE.
What’s striking about this new illusion is that even though it’s a totally static image, it creates a feeling of movement towards the center, as if you’re moving through a black hole or tunnel. It is this sensation that causes your pupils to dilate. Your brain believes you’re about to enter a darker environment and prepares your eyes to handle the decrease in light level it expects.
This tells scientists something about how our visual centers work, namely that they build our picture of the world on expectations, not actual physical stimuli. Ultimately, it’s for the best that our vision centers work this way. If they hadn’t, we probably wouldn’t have survived very long. That’s because sometimes the world moves faster than our brains can process it. It gets around this limitation by making educated guesses about the most likely outcome of events and providing you with that information as if it had already happened. Most of the time, your brain’s predictive engines are right and you don’t notice it. Illusions, however, disrupt our wiring.
“It explains how we can react to events that happen at speeds that exceed the speed of the nervous system. It happens every day. You drive a car, or you play sports, you play tennis or table tennis, how can you do that? By the time the image of the ball hitting the table reaches the part of the brain that controls your movement planning, it’s already several feet behind you. The solution is to correct by constructing the most likely representation of what the world would be like a bit in the future,” Laeng said.
This is why 86% of people who watch this illusion have a physiological response and their pupils dilate. Your brain does not react to the level of light as it currently exists. He reacts that he expects the light level to be slightly in the future, and he expects the environment to be darker.
The remaining 14% of study participants didn’t have the same reaction, and that’s likely due to how they process the image in their minds. If you remember the famous black and blue dress (or was it white and gold?), you have an idea of what’s going on here. How you perceived the dress depended on some prior assumptions your brain had made about whether it was photographed in bright light or in shadow. The same could happen here. People who do not have the sensation of moving through a tunnel make the correct prior assumption that the image is static. The rest of us are fooled by his visual trickery.
“We live in a virtual reality, really. What we see is what our nervous system creates. Your solid belief in indisputable reality and the reliability of your perceptions are not what they seem,” Laeng said.
If you have been deceived by this new illusion, by the dress, or by any number of other illusions you may have encountered in your life, you should not feel bad. We are all, quite literally, inventing as we go.