A viral photo reminiscent of a photo of a dress is making the rounds online. It shows a shoe and laces that are different colors to different people.
Some see a gray shoe with teal laces, while others see a pink shoe with white laces.
Wally Thoreson, a professor of ophthalmology and visual sciences at the University of Nebraska Medical Center, told The Omaha World-Herald that background light causes differences in perception.
Those who see a pink shoe see a blue light in the background, he said, while those who see a gray shoe see a white light.
“We see it as one or the other, not in between,” Thoreson told the World-Herald. “The brain has to sort of choose. I think people are surprised that what they see is not necessarily what their neighbor sees.”
According to a BuzzFeed poll, of nearly 500,000 votes, 87 percent see the shoe as gray.
But they may be wrong, the World-Herald reported. Vans footwear appears to be sell the shoe, and it’s pink.
The viral dress photo that was either white and gold or blue and black caused a similar debate. Business Insider spoke with the two women behind the photo of the dress.