Brain and Body

Peculiar Visual Illusion Makes You See A “Hole” In Your Hand

March 7, 2016 | Johannes Van Zijl

Optical illusion of a black hole in the middle of a hand
Photo credit: Screen capture from video by BrainCraft

Visual illusions can be a lot of fun, like this one, which causes a hole to emerge in the palm of your hand!

The strange phenomenon is known as binocular rivalry, which affects our visual perception. Our brain normally uses the visual input from images presented to each of our eyes, and then produces a three-dimensional image that forms the vision we perceive. However, when you present each eye with two very different images, the brain will try and suppress one of the images presented, to make the other more dominant. Instead of merging the two images into one, the brain alternates between the two images, thus causing you to perceive something unusual.

SEE ALSO: Trick Your Brain into Turning a Black and White Photo to Color

As Vanessa Hill from BrainCraft explains in the video below, you can try this optical illusion yourself — all you need is a narrow tube, which can be made from rolling up a letter-sized (A4) sheet of paper.

Place your hand in front of one of your eyes, roughly 2 inches (5 centimeters) away. Then look down the narrow tube with your other eye for about 10 seconds, focusing more on your sight through the tube, instead of on your hand. After some time, it will become apparent that a hole can be seen through the palm of your hand.

Here’s how binocular rivalry works:

The brain tends to suppress the visual input from the eye you used to look at your hand, because you were not focusing on it. But instead of cancelling the input it receives from the eye that was out of focus, the brain alternates between the two eyes, creating the illusion that the sight at the end of the narrow tube, has now formed a hole through your hand.  

This illusion is definitely worth trying next time when you are at a dinner party; you will have an optical illusion you can use to impress your fellow diners!


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