Seeing isn’t always believing. Sometimes, the eyes and brain are tricked into seeing things that may not be there. Optical illusions, for instance, are notorious for constructing shapes in certain ways that may cause our brains to “fill the gaps”. Or our eyes may be stuck on one perception of an image while another interpretation stares back, unseen despite being right before use. This is the case for this tricky brain teaser. How many legs are there really?
Can You Solve This Tricky Brain Teaser?
First, try to solve this on your own. How many legs do you see?
Now, you may not have noticed yet, but there are two kinds of legs in this photo. One wears red heels and the other wears black dress shoes. They lie opposite each other with the red shoes “standing” on the bottom of the pictures and the black shoes are upside down as if the wearer is kicking really high. If you can only see one version of the legs, try focusing on the black shoes or the red shoes. You’ll be amazed when your perception changes! Plus, once you see it, you won’t be able to unsee it.
Once people see both sides of this tricky brain teaser, many conclude with 22 legs in the picture. They often include the two legs cut off on either side of the picture. How many did you count?
How Do Optical Illusions Work?
You have probably seen many mind-bending pictures that require double-takes, such as the tricky brain teaser above. How many circles are there really? How could it look like the boxes are moving?
And in the case of this new optical illusion called “the scintillating starburst,” it looks like there are beams of light around the picture. However, these rays are non-existent but the brain “connects the dots” to create this effect. This image was created in 2019. Michael Karlovich, a visual artist with a background in neurosciences, designed the logo for his design company, Recursia Studios. “When I first saw the illusion I created, I instantly had a hunch I was looking at an effect I had never seen before. I was pleasantly surprised, but ultimately confused as to what the mechanism underlying the effect could be.” 
As seen in the above image, the “scintillating starburst” is a simple pattern with concentric wreaths that intersect with each other. But when someone looks at it, they see these intersecting points as bright dots. Really, there are only two colors in the picture, black and gray. The white spots are filled in by the brain. “The mind connects the dots to produce illusory line segments,” explained Karlovich.
A Mind of It’s Own
This ray effect may intensify or be fleeting depending on where you are looking and for how long. You can see the same concept in the famous Hermann grid illusion. There, the brain fills the gaps between the squares with black or gray dots. However, in both images, the contrast of colors is a considerable factor in the illusion.
“Our preliminary pilot experiments with color suggest what is most important is that there should be a high amount of contrast between the color of the background and the color of the lines making up the design,” Karlovich said. “The higher the contrast, the stronger the rays.”
The most incredible part is that when you try to focus on the gray dots in this tricky brain teaser, they disappear. After all, they are not really there; they only exist in your peripheral vision. 
Optical illusions could be humbling to examine. They teach us that our first impressions aren’t always correct, and neither is our second. Plus, they show us an invaluable insight into our brains and how they work. Most importantly, they teach us how to be aware of them.
“Visual illusions provide us insight into how the brain reconstructs the world,” said Karlovich. “They teach us about the assumptions and predictions the brain makes to construct our perceptions.”
An example of an illusion in real life is phantom limb pain. This occurs when people feel sensations in an amputated limb. It’s a strange phenomenon that doctors fix by tricking the brain into believing the limb has returned using a mirror.  As said before, seeing isn’t always believing when it comes to tricky brain teasers. The brain sometimes has a mind of its own.