The stink eye.

You know you’ve given it to someone or been on the receiving end.

Your face shows disgust, your nose wrinkles and your eyes narrow.

University of Colorado researcher Daniel Lee has been studying the stink eye and other facial expressions for eight years.

“We think the disgust expression comes from essentially sensory rejection so you’re trying to take in less of this thing that may be harmful to you,” Lee said. “The research we are doing is why we have these facial expressions we use for social communication and the idea is the same that Darwin had a long time ago – it’s that these expressions didn’t form as social behavior, they formed for a sensory function and we’re looking into the link between that older sensory function and their current modern sensory function.”

<p>Courtesy: Glenn Asakawa, CU Boulder</p>

To do the research, people come into the lab and make a bunch of facial expressions, such as fear or disgust.

The researchers measure the sensory intakes and how the visual field and sensory field changes or gets better.

They also ask the people what the expressions communicate and have them rate them on what they’re perceiving, whether the expression looks like fear or disgust, or more complex emotions like suspicion or awe.

Lee says facial expressions are like a universal language. They’re natural and automatic.

“You can go to another country and sort of have this human contact, this implicit mode of communication through your expressions,” Lee said. ”[Expressions] didn’t originate independently, they sort of all originated for the same reason for everyone, everywhere.”

When it comes to the "stink eye," Lee says the expression comes from sensory rejection.

“You’re trying to take in less of this thing that may be harmful to you, whether they are things you’ve ingested, or visual things,” says Lee.

Emotions are natural and come automatically for people, but there are some people who are not able to do that. Lee says he hopes his research can help people with autism, who may have trouble with expressions.

“It may be useful if you understand underlying grammar for the rules for why certain expressions convey certain emotions or mental states, then it would be useful to know what those rules are so you can teach those rules to other people,” Lee said.

Then people can use those rules to help them understand expressions.

You can read more about Lee's work here.