We've all made bad first impressions. Unfortunately, they are really hard to shake.

I have a handful of close friends who, when I first met them, I did not like. They seemed pretentious, ditzy or were making more eye contact with their phone than with me. For some, it took me a couple years to even get to know them because I couldn't get over the bad first impression they made on me.

I can't recall any of these said friends ever being outright rude, but it was subtle things that turned me off: their body language, their expression, their tone.

It also goes the other way. I have met plenty of people who I loved right away; who's first impressions were killer. They seemed really outgoing, witty and fun-loving.

It wasn't until later, once I got to know them, that I realized I got their personalities completely wrong. Because they had made such a positive initial impression, it made it that much harder for me to believe they weren't who I thought they were.

Both scenarios show just how powerful first impressions are. In fact, it takes only seven seconds for an impression to form. Only seven seconds for someone to make a snap judgment on who you are, how successful you are or how desirable you are.

That is super intimidating... but it also seems, for lack of a better word, stupid. Why do we do this?

The reason we size each other up like this when first meeting is because of our survival instinct. Our brain is simply trying to determine whether or not this stranger is a threat and if we can trust the person.

Unfortunately, this has a lot to do with how we look. We are vain creatures. Our appearance – how we hold ourselves, how we talk, our eye color, the straightness of our teeth – has a huge influence on what people think of us.

Fortunately, there have been several studies done and solid data gathered on what makes a good first impression. To find out what those factors are, watch the video above.

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