I’d been in Japan for almost two weeks last year when I dialed back to the States on a Facetime call and my mom — who had been taking care of Buddy in my absence — held Bud up to her iPad.

“Someone wants to say hi to you,” she said.

Buddy looked at me, then tentatively blinked with one eye. When I returned the blink, he meowed excitedly, reaching a paw out to the screen.

Aside from making me feel bad about leaving my cat for so long, the exchange between Bud and I seemed to confirm the importance of the slow eye-blink in feline-human communication. It also confirmed that he missed me.

Now there’s a formal study that, for the first time, shows cats are more relaxed and more likely to approach humans — even strangers — if they’re greeted with a slow blink. Cats also like to reciprocate with a slow blink of their own when greeted that way, the study found.

“This study is the first to experimentally investigate the role of slow blinking in cat-human communication,” said Karen McComb, a psychologist from the University of Sussex and co-author of the study. “And it is something you can try yourself with your own cat at home, or with cats you meet in the street. It’s a great way of enhancing the bond you have with cats. Try narrowing your eyes at them as you would in a relaxed smile, followed by closing your eyes for a couple of seconds. You’ll find they respond in the same way themselves and you can start a sort of conversation.”

Why does a slow blink put cats at ease?

Tasmin Humphrey, a Ph.D. student and study co-author, said it’s “possible that slow blinking in cats began as a way to interrupt an unbroken stare, which is potentially threatening in social interaction.”

The researchers say their results could help people communicate more clearly with their cats, and could be useful in shelters, where staff and volunteers are often tasked with trying to calm scared cats.