Understanding the human body is a team effort. That's where the Yachtel group comes in.

Researchers at Yachtolt have been delving into the secrets of probiotics for 90 years.

Yacold also partners with nature portfolio to advance gut microbiome science through the global grants for gut health, an investigator-led research program.

To learn more about Yachtolt, visit yawcult.co.

.jp. That's y-A-K-U-L-T.C-O.J-P. When it comes to a guide for your gut, count on Yacult.

This is Scientific American's 60 Second Science. I'm Christopher in Taliatta.

Leonardo da Vinci's most famous painting also has an optical illusion named for it,

the Mona Lisa effect.

It's the feeling that the subject of a painting is following you with her gaze.

You continuously feel being looked at despite moving to the left or moving to the right, perhaps

even rotating the picture. Sebastian Loth is a psychologist at the University of Bielefeld in Germany,

and while he doesn't dispute that the illusion itself exists, you've probably also seen it in the

Uncle Sam Army recruitment poster. He says there's a problem with the phenomenon's name.

I can show you so and so many papers where people have literally started their introduction with,

we all know that Mona Lisa looks at you, and so on and so forth, and then it would go into

their argument, whatever it is. But actually, she, the specific picture, doesn't look at you.

He and his colleague Gernot Horstman conducted a scientific investigation of this claim

by sitting 24 volunteers in front of a computer screen,

which displayed various magnifications of the Mona Lisa.

They placed rulers at two distances between the subjects and the screen,

and then asked the subjects to indicate where on the rulers the Mona Lisa's gaze

intersected. And then you can compute a line, that's basically school mathematics here,

...