Just this week, popular dating site OkCupid revealed that, like Facebook, it too had conducted experiments on its users. Through multiple experiments over many years, the site’s co-founders discovered that when it comes to a person’s profile, nobody really cares about the content, and instead, they judge the person by their pictures. So it makes sense that a new study would find that facial features are what drive first impressions.

The researchers noted that times are changing. As more people sign up for social media sites like Instagram, the frequency with which they take selfies will likely increase too. Because so much of what we know about some people is based on how we see them online, knowing how photos of their faces convey certain messages is important for understanding our subsequent behavior. “Showing that even supposedly arbitrary features in a face can influence people’s perceptions suggests that careful choice of a photo could make (or break) others’ first impressions of you,” said Richard Vernon, a Ph.D. student at the University of York, in a press release.

Previous studies had also found a link between first impressions and facial features. Two studies, one from 2000 and another from 2002, found that participants who were presented with a subject unconsciously altered their own facial expressions — even slightly — based on the expressions they saw. The effect can be seen perfectly in this lengthy ad for Beldent, the European version of Trident gum. Clearly, the stone-faced twin is the one who will be liked the least.

For the current study, the researchers looked at about 1,000 faces from photos on the internet, and with the help of judges, were able to narrow down the facial features that elicited a first impression. In all, there were about 65 features, which included eye height, eyebrow width, and cheekbone structure. Essentially, it was these features that people used to determine approachability, youthful-attractiveness, and dominance, according to the study’s abstract.

When the researchers reversed the exercise, and pieced together these facial features into cartoon-like faces, they were able to accurately predict the impression they were trying to evoke. “This study shows that despite enormous variation in ambient images of faces, a substantial proportion of the variance in first impressions can be accounted for through linear changes in objectively defined features,” the authors wrote.

So what does all of this mean? The researchers suggest that the study could have implications for people who have to provide photos of themselves to get jobs, such as actors, models, and the like. For these people, putting their best face forward could mean the difference. “In everyday life, I am not conscious of the way faces and pictures of faces are influencing the way I interact with people,” said Dr. Tom Hartley, lead researcher of the study, in the release. “Whether in ‘real life’ or online; it feels as if a person’s character is something I can just sense. These results show how heavily these impressions are influenced by visual features of the face — it’s quite an eye opener.”

Source: Vernon R, Sutherland C, Young A, Hartley T. Modeling first impressions from highly variable facial images. PNAS. 2014.