ONE popular optical illusion has left people baffled and wondering what it means for their brains.
It was originally released in 2003 as a GIF animation of a pirouetting female dancer.
Created by Japanese web designer Nobuyuki Kayahara, the optical illusion works by using motion to stimulate your brain.
Some observers see the figure spinning clockwise, while others see her moving counterclockwise.
And some people may see the figure spin one way and then suddenly go in the opposite direction.
What does it mean for my brain?
For years, articles have labeled the optical illusion as a test to see if you are "right-brained" or "left-brained".
Basically, if you see the dancer spinning clockwise, people say you are using more of your right brain.
And if you see it moving counterclockwise, you are more of a left-brained person.
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However, that theory has been debunked by experts – or as scientist Arthur Shapiro told VICE: "That's just gibberish."
Instead, the illusion is a reversible two-dimensional image that can tell us more about how vision works.
How does this illusion work?
Reversible, or ambiguous optical illusions work because they lack depth cues – this confuses your brain.
And when your brain is perplexed, it undergoes a process called "unconscious inference."
This process helps your brain find meaning – or conclusions – without enough evidence. In other words, it's guessing.
As a result, your brain may sometimes perceive the dancer standing on her left leg and spinning to the right.
And sometimes, it may perceive the woman as standing on her right leg and spinning to the left.
Most people, if they look hard enough at the image, will see her spin in both directions.
"Silhouettes are supremely ambiguous," Shapiro said.
"If you added data to the spinning girl, like a pair of colorful Lululemon pants, your brain would solve the illusion faster."