The glasses-as-disguise trope is one we all know. Clark Kent somehow masks his identity as Superman with a pair of thick frames. Kara Danvers somehow is able to pull off the same shenanigans as Supergirl. And we know from the glory of the late 1990s that behind every pair of glasses hides a hottie.

While it may seem dumb that a pair of glasses could somehow totally obstruct someone’s identity, studies show that they actually can. Nope, it’s not necessarily a case of prosopagnosia; people are just really bad at recognizing strangers once they have glasses on.

In a study published Thursday, psychologists at the University of York showed participants paired faces — the same face but shown twice in a particular way, such as both faces with glasses, both faces without glasses, and one in which only one face had glasses. In the photos where the two identical faces were both either wearing glasses or both not wearing glasses, accuracy at determining whether both faces were the same person was 80 percent (still, not great). Accuracy when only one of the faces wore glasses was 74 percent, which the researchers consider a “statistically significant decrease.”

“In real terms, glasses would not prevent Lois from recognizing that Clark is in fact Superman as she is familiar with him,” said co-author Kay Ritchie in a statement. “For those who do not know him, however, this task is much more difficult, and our results show that glasses do disrupt our ability to recognize the same unfamiliar person from a photo-to-photo.”

"Wow, you look really pretty without your glasses" was an actual line used here.

This study adds further proof to the fact that while we are decent at recognizing familiar faces, we’re pretty bad at recognizing a face we’ve only encountered a few times. In a 2015 study, people given an unlimited time and optimal viewing conditions to match security footage to photographs of people in that footage only correctly matched the two 70 percent of the time. Researchers theorize that we have this poor matching system because the unfamiliar and familiar are processed in different ways by the brain — the unfamiliar are only processed as visual stimulus patterns, the brain scanning the facial regions for recognition. Something like glasses, it’s hypothesized, throws off this process.

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