As a user experience expert at Nielsen Norman Group, Kate Meyer has watched a lot of people use a lot of websites. But her favorite quote comes from a young adult–under 25–talking recently about navigating a flat web design: “I don’t [know what’s a link]. I just start clicking and praying that it works.”

It’s a funny and telling comment, and it reveals that a lot of research remains to be done about whether young people intuitively understand flat UI better than their parents–and, even if they do, whether designers should design specifically for young people based on the idea that they’re better at navigating flat design. “There’s an underlying assumption that flat UIs are targeted at millennials,” Meyer writes. “So it’s okay if older users don’t quite ‘get’ how to use flat UIs, these designers argue.”

Over the past year, Meyer—who teaches conferences about designing for young users—has examined how different users approach flat interfaces, offering a compelling argument against using flat design as a way to appeal to young users. Or, as Nielsen Norman Group’s Don Norman and Bruce Tognazzini put it in their screed against Apple’s emphasis on flat design and minimalism, “So what if many people can’t read the text? It’s beautiful.”

Testing Flat Design

Flat design generally describes minimalist interfaces that eschew skeuomorphic flourishes: drop shadows, gradients, and the like. Recently, Meyer ran a study that asked young and old users to rate the attractiveness of five fictional websites. Four were “flat,” while one was skeuomorphic, rife with drop shadows and signifiers. NNG asked almost 500 users—half between 18 and 25, half over 35—to rate each site aesthetically.

A flat website design versus the skeuomorphic control design.

It turned out that younger users liked the flat websites a lot more than their older counterparts—by more than half a point on a 1 to 10 scale. Older users said the flattest website designs were “boring,” while younger subjects described them as “professional.” Fascinatingly, the youngs rated the skeuomorphic design as just as attractive as their “parents” did, with both age groups describing a shadow-stuffed website for a fictional steak house as “professional” and “trustworthy.”

So younger people found flat designs better-looking. Old people didn’t like them. That may not surprise you–especially if you’ve ever watched an older person try to navigate a super-flat website for a few minutes. But whether or not a user likes a design is only half the story. And it turns out, it doesn’t have terribly much to do with how well they navigate it.

Liking Something Doesn’t Make It Usable

In her past research on flat design, Meyer closely studied how well young adults could navigate flat sites. She observed something odd: While young people seemed faster at navigating the designs, they also indicated they didn’t really understand the UI intuitively. In fact, for the most part they seemed to have, uh, pretty much no idea what they were doing.