Though one may think it’s difficult to forget a beautiful face, it may be even harder to omit an unattractive one, according to new research out of the University of Jena in Germany.

Researchers found that people are actually more likely to remember and recognize faces that aren’t as attractive but have distinctive features, despite popular belief. “On the one hand we find very symmetrical and rather average faces appealing,” Dr. Holger Wiese, an author of the study from the Friedrich Schiller University Jena, Germany, said in a press release. “On the other hand, people who are perceived as being particularly attractive stand out by additional traits, which distinguish them from the average.” Such features, or "additional traits," could be anything from big eyes or a distinctively-shaped mouth, Wiese says. “We tend to remember those faces well,” he said.

Wiese and his co-authors Carolin Altmann and Dr. Stefan Schweinberger found in their study that participants were more likely “to remember unattractive faces than attractive ones, when the latter didn’t have any particularly noticeable traits,” Wiese said. This means that if you’re attractive yet nondescript, people may be more likely to notice your less attractive neighbor instead — if they have a quirky feature like a unique nose or exotic cheekbones.

The researchers showed photos of faces to the participants of the study, with one half of the faces considered “attractive” and the other half less attractive. They were all, however, thought to be unique or distinctive-looking. Each face was shown for only a few seconds, during which the test subject would have to memorize the features. Afterward, they were shown the faces again and asked if they recognized them. They found that the participants were able to recognize the less attractive faces more than the pretty ones.

“Until now we assumed that it was generally easier to memorize faces, which are being perceived as attractive — just because we prefer looking at beautiful faces,” Wiese said in the press release. However, this study showed some evidence that this notion may not necessarily be as true as we thought.

So what makes a face attractive, from a solely physical viewpoint? What researchers have found is that the more average a face is, the more attractive it is. Sometimes small details like full lips, or bigger eyes, will make a woman's face appear more attractive. But is there ever a particular ratio or measurement that can capture facial beauty?

"People have tried and failed to find these ratios since antiquity," Pamela Pallett, a postdoctoral fellow in psychology at UC San Diego, said in a press release about a 2009 study. Pallett explains that ancient Greeks believed the "golden ratio" [phi] was a signal of beauty, and used it in architecture as well as art. "But there was never any proof that the golden ratio was special," she said. "As it turns out, it isn't. Instead of phi, we showed that average distances between the eyes, mouth, and face contour form the true golden ratios." Pallett's study claimed that there are two "golden ratios" that define beauty — one regards facial length, which is more attractive if the vertical distance between eyes and mouth is about 36 percent of the face's length. The other is the horizontal distance between the eyes, which is considered ideal if it's about 46 percent of the face's width.

However, there's usually far more to facial beauty than these two "golden ratios," as some famous beauties like Angelina Jolie don't quite match up to these measurements. Instead, beauty is most likely a compilation of symmetry, ratios, and both average and distinctive features — as well as, of course, your personality.