At some point between your first smartphone and your fifth dating app, something changed about what you found attractive. The preferences got more specific. The list got longer. And somehow, the person sitting across from you at a perfectly decent first date started feeling like a disappointment before they’d even finished their drink.

There’s a psychological explanation for how that happened, and it predates Instagram by about 50 years. In 1968, psychologist Robert Zajonc documented what’s now known as the mere exposure effect—the finding that repeated exposure to something makes it progressively more appealing. It’s why the coworker you barely noticed at the start of a job becomes someone you can’t stop noticing six months in. Familiarity, at a neurological level, reads as safety. Safety reads as attraction. The brain doesn’t reliably distinguish between the two.

Social media didn’t invent this process. It just got there first. According to Body+Soul, what used to happen through actual proximity—running into the same person, building familiarity over weeks, letting attraction develop at its own pace—now gets outsourced to an algorithm.

Why Dating Apps May Be Making It Harder to Feel a Spark

Every second of hesitation is information. A face that holds your attention longer than the last one, a profile that slows your scroll, all of it feeds back into the system. It adjusts what it shows you, gets even more precise, and keeps going—until the app has built a picture of your ideal person and you’ve started holding everyone you meet up against it.

Harvard comparative literature professor Moira Weigel told the Harvard Gazette that dating apps use algorithms to “optimize for certain kinds of partners”—a calculated approach that runs counter to how romantic attraction has functioned for most of human history. And the cost shows up in real life. An actual person sitting across from you gets evaluated against an image assembled on a screen, and if they don’t clear it fast enough, the whole thing is over before it starts. People don’t arrive fully formed. The most compelling thing about someone almost never surfaces in the first three minutes—and three minutes is around how long the algorithm has trained people to give it.

Most people can point to at least one relationship they never would have predicted, because what they ended up loving wasn’t obvious at first glance. That requires patience. It requires giving someone enough time for the mere exposure effect to do what it was always supposed to do—work on a real person, in real life, rather than a feed designed to keep you scrolling.