One such illusion is this image, which depicts a series of dots with a large black hole in the middle.
When you stare at the image, it may appear as if the big hole is moving, growing, or expanding, but the image is actually static.
Why does the image appear to be moving?
The illusion appears to move because the pupils in your eyes subconsciously adjust to the light around you, dilating when it’s dark to capture more light and constricting in bright light to avoid overexposure.
When you look at this illusion, it may appear as if the hole is changing in size, but this is actually just being caused by your pupils reacting to the image.
Using an infrared eye tracker, psychologists found that the greater a participant’s response to the illusion, the greater the pupil dilation response.
The researchers believe the illusion works because the gradient of the central hole makes it appear as if the viewer is entering a dark hole or tunnel, causing the pupils to dilate.
They also found that the effect of the illusion varied against different colored backgrounds and was strongest when the black hole was on top of magenta.
Bruno Laeng, a psychology professor at the University of Oslo and author of the study, told dem New York Times: “There is no reason per se that the student should change in this situation, because nothing in the world changes.
“But clearly something has changed in my head.”
“The brain tries to anticipate the future”
Visual illusions can show how our brain tries to anticipate the future in order to perceive the present, says Dr. length
It takes time for a stimulus like light to reach our sense organs, which have to transmit it to the brain. The brain then needs time to process this and understand the information.
Therefore, seeing an expanding hole in the illusion is not a mistake, but the result of the brain trying to navigate an uncertain and changing world. It is adaptive to predict the future by dilating your pupils in anticipation of going to a dark place.
dr Laeng explained that when the eye is presented with a scene, the brain “analyzes what it sees and builds, constructs a possible scenario and adapts to it”.
But not everyone is fooled by the illusion, with 14% of study participants saying they saw no change or “movement” when looking at the images. dr Laeng says a minority may only see the image in two dimensions.
Another example of a dress illusion that went viral on the internet a few years ago, with some people seeing it as white and gold while others were able to see blue and black.
The picture that was first posted on tumblrquickly spread around the world via Facebook and Twitter feeds as people argued over which color it was.
Cedar Riener, associate professor of psychology at Randolph-Macon College, explained this BuzzFeed that the differences in color perception are related to how our brain interprets the “amount of light entering our retinas”.
This luminance is a combination of how much light shines on an object and how much it reflects off the object’s surface.
This means that our individual sensitivity to the photo’s backlight affects how we see the object in the image, as in the expanding pinhole illusion.
Reiner explained, “Some people decide that a blue and black (or less reflective) dress has quite a bit of light.
“Other people decide that there is less lighting on a white/gold dress (it’s in the shade but more reflective).”
dr Laeng added: “The information we’re getting from the world is pretty vague.
“The brain goes into constant guessing mode, we kind of have to find the best solution, but there are multiple possibilities for the same type of input.”