Everybody judges.

Within a few seconds of seeing someone - whether it's on a date or at the grocery store - we decide a number of things about them, from how smart they are to how likely they are to commit a crime.

Surprisingly, our first impressions can be remarkably accurate in some instances. In others, they can be wildly off-base.

Here are a few of the things that we determine about people based on how they look.

1. If you're attractive, people assume you have other positive traits as well.

Thanks to a phenomenon that social psychologists call 'the halo effect,' we tend to assume that good-looking people possess other positive qualities aside from their looks, such as intelligence and commitment.

Daniel Hamermesh, a University of Texas psychologist who studies beauty in the workplace, found that, among other things, this cognitive bias means good looking people tend to get paid more in the workplace.

Similarly, in a study of male undergrads who were asked to evaluate an essay written by an unnamed female peer, the participants judged the writer and her work more favourably when they were shown a photo of an attractive woman whom they believed to be the writer, as opposed to when they were shown a photo of an unattractive woman or no photo at all.

2. People can also get a surprisingly accurate read of your personality from a photo.

People can tell a surprising amount about your personality from your portrait.

In a 2009 study, researchers showed participants the photos of 123 undergrads from the University of Texas at Austin in which the undergrads either were told to have a neutral expression or were allowed to pose however they wanted.

No matter which position the people took, the viewers were better than chance at judging the following: how extroverted they were, how high their self-esteem was, how religious they were, how agreeable they were, and how conscientious they were.

3. Your facial structure can give people clues about how aggressive you are.

A small 2013 study by researchers at the Center for Behaviour Change at the University College London suggested that men with higher testosterone levels were (not surprisingly) more likely to have wider faces and larger cheekbones.

Men with these facial features also tended to have more aggressive or status-driven personalities.

4. People also use your facial structure to make judgments about how strong you are.

In a 2015 study, scientists showed people photos of 10 different people with five different facial expressions and then asked them to rate how friendly, trustworthy, or strong the photographed person appeared.

Not surprisingly, viewers tended to rank people with a happy expression as more friendly and trustworthy than those with angry expressions. They also tended to rate people with broad faces as stronger.

5. If you look "untrustworthy", you're more likely to be seen as a criminal.

It's unclear why some of us appear more trustworthy than others, but this quality may have life-changing consequences.

Researchers from Israel and the UK had volunteers look at photos of men and women that had been randomly selected from two photo databases and rate the emotional state, personality traits, and criminal appearance of the people pictured.

The first set of photos came from a police mugshot database; the second were controlled photos in which actors had been told to look happy, neutral, or angry.

Regardless of where the photos had come from, people who were rated less trustworthy and more dominant also tended to be seen as criminals. In the controlled photos, angry faces were seen as the most criminal.

6. Other underlying health issues may be seen first in the eyes.

Doctors can diagnose numerous conditions just from looking at your eyes. Red spots in the retina, the light-sensitive layer at the back of the eye, can be a sign of diabetes.

When blood-sugar levels get too high, this can block the blood vessels in the retina, causing them to swell and burst.

7. Your face might not tell the whole story. For men, finger length has been tied with cancer risk.

Scientists studied the finger lengths of 1,500 patients with prostate cancer and 3,000 healthy men over a period of 15 years by asking them to look at pictures of hands and choose one that resembled their own.

Men who said their index fingers were the same length or longer than their ring fingers were one-third as likely to be diagnosed with prostate cancer over the course of the study as men whose index fingers were relatively shorter, and the effect was even larger for men under the age of 60.

Keep in mind that the study was based on the men's reported finger length, not actual measurements, so further studies are probably needed to confirm the findings.

8. And your height could reveal your risk of certain diseases.

Studies suggest that taller people have a lower risk of heart disease, while shorter people may have lower rates of cancer.

The effects are believed to do with the amount of growth hormone produced, which can protect against some diseases but increase the risk of others. The findings, however, do not necessarily mean that being tall or short will prevent you from getting either disease.

This article was originally published by Business Insider.