KYOTO, Japan — What is the relationship between U.S. diva Lady Gaga and a Japanese professor in psychology?

The answer is: Lady Gaga’s new album “Artpop,” which just hit No. 1 on the Japanese albums chart, features an optical illusion artwork designed by Akiyoshi Kitaoka, a professor at Ritsumeikan University in Kyoto.

“I’m glad my artwork drew people’s attention,” he said. “I hope people all over the world will see how interesting optical illusions are.”

Kitaoka, 52, made the optical illusion artwork titled “Gangaze” in 2008 and displayed it on his website. It was later used for Lady Gaga’s CD cover.

The image contains objects that look like spikes on a sea urchin and gives viewers an impression that those spikes are moving and popping out. People working with Lady Gaga asked Kitaoka for approval to use the image.

At the university, Kitaoka teaches psychology. Originally studying animal psychology, Kitaoka came up with an idea to use optical illusions when he was studying the senses of monkeys.

Kitaoka started designing images using a personal computer in the mid 1990s.

Optical illusions can make people perceive that a motionless image is moving and make a graphic image look different from its actual form. These illusions have raised fundamental questions about how people perceive the outside world through their eyes and brains.