With just a split-second glance at a person's face, we draw conclusions about her leadership skills, vigor, and intelligence.

It's also very remarkable how firmly our conclusions can stick, even when the persons personality begs to differ.

Students in one study spent just a few minutes talking to a fellow classmate before recording their first impressions.

Nine weeks later, the students who had formed positive first impressions of one another had gravitated toward relationships; the rest didn't go on to be friends.

They may have been right that not jumping to conclusions, but research suggests you're going to do so anyway.

Read on to understand why.

We know what we like:

Beauty is indeed in the eye of the beholder. Volunteers exposed to faces that had been prejudged as beautiful or homely registered a response in just 13 milliseconds, below the threshold for conscious awareness.

The subjects insisted they saw nothing, yet when asked to rate the attractiveness of the face they'd just viewed, they accurately identified those that were better-looking in a 2005 study published in Emotion.

Some people have a face for politics:

Masculine features, including lower eyebrows and cheekbones, were associated with dominance, according to a 2014 study at the University of York in England.

In other studies, subjects noted that high eyebrows, which open up the eye, made a person seem warm and naive.

People make judgments about traits like trustworthiness, competence, likability, and aggressiveness with remarkable speed. A group of Princeton researchers found it took just 100 milliseconds.

Your eyes show their age:

The limbal ring, i.e the dark area around the edge of the iris, becomes less noticeable with age or ill health, so dark ones may suggest vitality.

Subjects judged faces with clearly visible limbal rings as more attractive than identical faces without rings in a 2011 University of California at Irvine study. Acuvue has a line of contact lenses that darken the ring.

A smile is a potent anti-ager:

A smile makes a person look more approachable. We all know this.

German researchers found that a broad smile also makes middle-aged people look younger.

That's probably a result of two factors: first, what researchers called the "halo effect," wherein a friendly face is just more attractive than a neutral one, and second, the fact that wrinkles on a smiling face seem temporary.

Perspective matters:

Women were considered more attractive when their faces were tilted slightly downward, which is what they look like from above.

Their faces were rated as less attractive, and less feminine, when they were tilted up, simulating a view from below, researchers found in a 2010 study published in Evolutionary Psychology.

Yayy for the selfie lovers.

Wear (some) makeup:

Women wearing moderately colorful makeup were judged as more likable, competent, and trustworthy than those with bare faces, whereas a face with a lot of color didn't register all of those same positive impressions, according to a study at Massachusetts General Hospital.

Always play it cool: A relaxed smile and an energetic stance, versus a tired or tense one, naturally correlated with not just likability and self-esteem but also emotional stability in one study. People with a tired or tense posture were seen as lonely and unstylish.

Put your best face forward:

A front view (as opposed to a side one) makes a person look more youthful and approachable in pictures, according to a 2014 British study.

A University of Virginia survey of Facebook users found that those with broader smiles in their profile pictures had greater life satisfaction three and a half years later.

Psychologists theorized that a super-sized grin "may seem more friendship-worthy" and thus lead to happier personal relationships.