For many animals, a direct gaze into their eyes constitutes a challenge. Gaze into the eyes of a dog you don’t know well and you’ll be picking a fight, and a cat on edge will keep their eyes laser-locked on a perceived threat.

As cat aficionados have long suspected, you can break the ice with a cat who’s sussing you out by slowly blinking your eyes once to communicate that you’re letting your guard down. Seeing that you’re not in attack mode, the cat will usually return the gesture and relax. Call it the “slow blink.” Others consider it a “cat smile” for the facially inscrutable beings.

Now scientists from the University of Sussex and University of Portsmouth in the U.K. confirm the magic effect of the slow blink in a study published in Scientific Reports called “The role of cat eye narrowing movements in cat–human communication“.

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“It’s something that many cat owners had already suspected, so it’s exciting to have found evidence for it,” says senior author Karen McComb.

“It’s definitely not easy to study natural cat behavior,” says co-author Leanne Proops, adding that “these results provide a rare insight in to the world of cat-human communication”.

Read more: Big Think