Here's How We Quickly Judge Human Faces

Have masculine or feminine features? A big smile? Characteristics like these, it seems, are central to our snap judgements of people's faces. Using a computer model, researchers have figured out how different features affect our first impressions, the BBC reports. The system is based on 1,000 pictures of different faces gathered online. In a study, researchers had respondents give opinions of these faces, focusing on approachability, dominance, and attractiveness. Researchers then created a mathematical model that translated those opinions into distinct facial measurements—an effort to "crack the code of first impressions," notes Smithsonian.

The result was a computer program that generates cartoon faces intended to be dominant or submissive, approachable or off-putting. Another batch of study subjects offered their opinions of the cartoons—and they fit the computer's assessments. Masculine features and a good tan were apparently tied to the perception of dominance, while smiles were associated with approachability, LiveScience reports. Knowing how first impressions work may be particularly important these days: "Whereas in the past, we got to know people through meeting them in the flesh, increasingly, our first contact is online, and our first impressions are based on the images we provide on social media profiles," says the study's lead author. Of course, what's attractive could change a lot in the next century. (More faces stories.)