A baby grinning at a meat grinder as pulverized flesh extrudes into a bowl. A slice of pizza in a pot of boiling water. A toilet, barely visible, installed inside the mouth of a cave. A teddy bear with human teeth. All of these images, in the eyes of the internet, are cursed. The found photos are unaccountably horrifying, hilarious, and baffling all at once, examples of one of the web’s most enduring meme forms, a bit of internet culture at its most wonderfully, deliberately senseless. They are the perfect online attention trap: Once your eyes land on a cursed image, it’s difficult to look away. And when you do, it’s hard not to scroll on for more.

The genre seems to have started on Tumblr in 2015, with a man standing in a room full of tomatoes. He’s probably someone’s nice grandpa, but there’s something unsettling about the indoor farmer’s market, with its fuzzy focus and boxes of produce piled up on oil drums. “This image is cursed,” reads the caption, posted by Tumblr account CursedImages. Tumblr users began applying the “cursed image” label to any image they found disturbing, usually due to bizarre subject matter or poor image quality. From Tumblr, the meme spread to Twitter, where @cursedimages (along with its cousins, @scarytoilet and @darkstockphotos) gained popularity and media notoriety during the 2016 election season for their photos of feet with lit cigarettes between each toe or cabbages being stabbed with over a dozen knives. Interest in the meme has been spiking again all spring. Whatever the appeal of being vaguely creeped out is, it’s not fading.

Emma Grey Ellis covers memes, trolls, and other elements of internet culture for WIRED.

Shocking images are classic internet entertainment: Before they get to social media, many cursed images start out on old-web sites that focus on far gnarlier fare, such as snuff films, gross-out medical photos, and all things scatological. That suggests the appeal of cursed images might be related to the morbid curiosity inspired by more outre photo genres. Think of them as gateways at which most users happily stop, going no further.

People’s reactions to shocking imagery have been well studied. According to Dario Maestripieri, a behavioral scientist at the University of Chicago, humans know that violence is likely to impact their lives and instinctively seek out violent content to learn more about it. The appeal of disgust, which Maestripieri says is experienced by a smaller number of people, is a little more murky. “From an evolutionary perspective, we should be avoiding those things,” he says. “Disgusting stimuli can carry the risk of infectious disease.” In his research, participants can bare looking at disgusting images for a shorter length of time than any other category. But then how do you explain 2 Girls 1 Cup? “There’s an aspect of personality at work,” he says. “You might argue that if you’re really disgusted, you’re aroused. Some people are sensation-seeking.”

It’s the sensation-seeking piece that seems most related to the allure of cursed images. Whatever they make you feel, it’s never nothing. “Humans evolved to be drawn to things that are novel,” says Margee Kerr, a sociologist who studies fear. “We're descendants of humans who had the curiosity and motivation to go out and explore, but also the ability to quickly notice and take action when confronted with something new.” In modern society, it’s made us magpies, hunting for shiny weirdness. It’s why people love travel photos and deepsea fish and why “Never Seen Before” is delicious clickbait. You’ve probably never seen a person in an Elmo costume splayed out on a bed like one of Jack’s French girls. Your brain rewards you for your discovery.