Chanan Walia, a sophomore at University of California, Berkeley, can’t remember the last time he used a doorbell or even knocked on a door.

At home, his father installed a fancy, Wi-Fi-connected doorbell. Mr. Walia, 19 years old and a computer science major, says he just isn’t comfortable ringing them. He and his friends have become so accustomed to texting one another upon arrival, he says, that the sound of a doorbell feels like an unexpected jolt.

“Doorbells are just so sudden. It’s terrifying,” says Tiffany Zhong, 20, the founder of Zebra Intelligence, which helps companies conduct custom research and gather insights on people born in the past two decades.

There’s no published research about doorbell phobia, but it’s a real thing. In a poll by a Twitter user earlier this month that got more than 11,000 votes, 54% of respondents said “doorbells are scary weird.”

Some millennials and Gen Zers say they won’t even consider answering a ring at the door until they’ve checked the security camera.