You’re sitting on an airplane, and before you pick a movie — or maybe despite having done so already — you start watching someone else’s screen. Though you can’t explain exactly why you’d rather watch a faraway show on a too-small screen without any audio, you can’t look away.

Maybe it’s easier to leech off someone else’s movie selection than a choice of your own. Maybe it’s the risk of being caught, the allure of spying on a private moment. In-flight movies are just better on a stranger’s screen.

Why we spy

The appeal of peeking at another person’s in-flight entertainment is well-documented online.

On X, formerly known as Twitter, a user confesses: “i cannot focus on a movie on an airplane unless it is on someone else’s screen and i am also watching a movie and listening to music and reading a book.” Another writes that “the voyeurism of watching a movie on someone else’s screen just adds to the experience.”

These sneaky experiences are more common now than they were a few decades ago, when seat-back, personal screens first started to take hold in the airplane industry. But “shoulder surfing” is nothing new. The term refers to the act of spying on someone else’s phone or laptop screen, ATM or other electronic device behind their back — a practice that’s more common than one might think.

Mohamed Khamis, an associate professor in computer science at the University of Glasgow, studies the privacy and security implications of technology. He says that shoulder surfing is so popular in part because it doesn’t require any special skills, unlike hacking into accounts or tapping phone calls.

The behavior also carries little risk of getting caught. While researching people’s ability to recognize when they are being shoulder-surfed, he found that it often goes unnoticed; people underestimated the amount of times others were spying on their screen.

The impulse to shoulder surf, he added, can be simply explained by boredom and curiosity. It’s why he has looked over at other passenger’s screens while on a flight.

“This is something that’s been around for a long time,” he said. “Even when people were reading books and newspapers and stuff, people would also look at each other’s content.”

Habiba Farzand, a PhD student on Khamis’s team, said while shoulder surfing can happen anywhere, it’s most common on public transport. This often means trains and buses, but can apply to airplanes as well. “And sometimes, the device is right in the line of sight,” she said.

On an airplane, it can be hard for travelers to avoid looking at the screens in front of them, even if unintentionally.

In their research, Khamis and Farzand have found that the risk of shoulder surfing can affect people’s behavior when using screen technology in public. This can mean dimming a screen, tilting devices away from potential prying eyes or turning screens off altogether.

On airplanes, where any sort of privacy is difficult to come by, these response behaviors can take on different forms.

In a popular post last year, one generous Reddit user revealed that they make sure to turn on closed captioning on any in-flight movie they watch, “in case someone else is watching my screen.”

What are the best movies to watch on a plane?

On Reddit, a perennial hotbed of internet discourse, a user who was “currently watching someone four rows up watch Spiderman Far From Home” asked others about the best movies they’ve seen for the first time on someone else’s in-flight entertainment screen. Responses ranged from Hugh Jackman’s “The Greatest Showman” to “Bohemian Rhapsody” to “the entire Harry Potter franchise without trying.”

When you’re stuck on a plane, you may adopt different standards for the type of movie you want to watch.

“Picking a movie on a plane is hard because you don’t want to watch something very bad (obviously) or very good (too good for a plane!),” declared “Jeopardy!” host Ken Jennings in an X post this spring.

Good genres for plane watching, he continued, included rom-coms, “regular athlete,” “Quiet British person … does something eccentric” and “Michael Clayton for the 1,000th time.”

Missing from Jennings’s highly specific genre list: slasher movies and overtly steamy flicks. Both genres are ripe for producing uncomfortable experiences should the viewer become aware of the many other eyes watching their screens.

Considering the possibility of prying eyes is an individual choice, but it’s courteous to steer clear of content you wouldn’t want other passengers — especially children — to see.

But in rare cases, the choice is made for you. For passengers on a recent United flight, a technical mishap forced the entire flight to watch Will Ferrell’s 2004 comedy “Anchorman,” according to a popular Reddit post. Pictures from the flight show rows upon rows of Ron Burgundy.