We all know how incredibly hard it can be to change a bad first impression, but if that already makes you nervous when meeting someone for the first time, I have bad news for you.

Science just discovered exactly how long first impressions linger, and the information won't do anything to soothe the anxiety of anyone who just met their boss (or dream client) for the first time a few too many cocktails in at the office holiday party.

Time, apparently, doesn't heal bad first impressions.

To test the durability of quick first impressions, a team of researchers at Cornell University had 55 volunteers view pictures of a woman they had never met before. In some of the photos she was smiling, in others, serious-faced. After viewing the picture the subjects rated her personality for qualities like extraversion and friendliness. Then these same volunteers actually met the woman in real life between one and six months later.

Despite only having ever glimpsed their new acquaintance in a photo and up to half a year elapsing between that limited interaction and the actual meeting, the impression of the woman's personality the subjects received from the photograph still heavily colored their face-to-face conversation.

And this happened even though all but four of the subjects didn't even consciously recall ever having seen the woman before. (Those who did remember her were excluded from the analysis of the results.) That means that even if a first impression is seemingly forgotten, it's not really forgotten - even months and months afterward.

Are first impressions self-fulfilling prophecies?

Not only does that show that our minds hold on tenaciously to first impressions, but according to Cornell psychology professor Vivian Zayas, who participated in the research, but that might also be only part of the reason our initial assessments of people are so durable. First impressions, she suggests, might also act as self-fulfilling prophecies.

Study subjects who had a warm and positive impression of the woman from the earlier photograph probably behaved differently upon meeting her, speculates Zayas. "They're smiling a little bit more, they're leaning forward a little bit more. Their nonverbal cues are warmer," she commented. "When someone is warmer, when someone is more engaged, people pick up on this. They respond in kind. And it's reinforcing: The participant likes that person more."

Unfortunately, these feedback loops can be negative as well as positive, with awkwardness and chilly behavior reinforcing each other after a meeting gets off on the wrong foot.

So what's the takeaway? Simply that you really, really need to try and make a good impression the first time you meet someone.