People often make assumptions about each other’s character traits based on facial features. While, to a limited extent, it seems like we can actually glean some reliable info about personality traits from someone’s face, we can also add a heaping pile of bias on top of that too. A paper in PLOS One explores one of these biases: the more attractive we think a person is, the more we’re inclined to think they’re intelligent. This “attractiveness halo” means that we’re likely to overestimate the intelligence of people we find attractive.

One of the complications in assessing something like this is that people vary in what they believe “intelligence” is. This is an entirely separate question from what any scientific consensus actually says about the concept of intelligence and how we measure it. Regardless of what science says, people will still have their own understanding of what the idea means, believing that intelligence is the result of things like a “growth mindset,” of conscientiousness, or of genetics.

This makes it a bit difficult to do an experiment. These different definitions of intelligence, the authors write, suggest that people will consider different things in a face to signal intelligence, leading to “less accurate perceptions of intelligence.” So just asking for people to rate the intelligence of a series of faces would be unlikely to identify our perceptions with a huge amount of accuracy. To account for this, the researchers decided to also ask about other ratings that could capture various beliefs about intelligence: conscientiousness and academic performance.

The faces participants were asked to rate couldn’t just be drawn from a database of faces used in research—the researchers had to have matching data that could give some indication of intelligence. They asked students at the University of St. Andrews to sit for photographs and consent to their university records being accessed. Only the 100 most “standardized” faces were used; in this case, that meant faces with a neutral expression, no make-up or jewellery, clean-shaven, and Caucasian (to control for racial bias). A GPA based on university records was calculated for each of these 100 “models."

Participants for the study were then recruited from Amazon Mechanical Turk and asked to rate each face for its attractiveness, intelligence, conscientiousness, and academic performance. Again, the researchers accounted for racial biases by eliminating data from non-Caucasian participants, leaving 124 participants in the analysis.

This allowed each of the 100 faces to be given average scores for how attractive, conscientious, intelligent, and academically high-performing it was perceived to be. The researchers could compare these scores to the GPAs of the students and explore any correlations between the ratings.

They found that more attractive faces were more likely to be highly rated as intelligent, conscientious, and with high academic achievement—but in reality, there was no relationship between attractiveness and real-world academic achievement in the form of GPAs.

What the researchers most wanted to see was how much that extra attractiveness was giving all the other perceptions a boost. That is, if you take away the benefits that a pretty face gives, can people tell anything simply by looking at a face?

To test for this, they controlled for attractiveness in the ratings and calculated what the other ratings would have been if all the faces had been rated equally attractive. With the “attractiveness halo” removed, the conscientiousness ratings that were left over were highly correlated with actual academic performance. This was the only measure that was any good at linking up with real-world academic performance. Even with attractiveness controlled for, ratings of perceived intelligence and academic performance didn’t match up with reality.

A lot of research on face perception focuses on whether our perceptions match up with reality and where misperceptions can have disturbing real-world impact. This research fills a gap in telling us exactly what kinds of errors we might be making in judging other people. “Facial impressions have consistently been shown to influence our opinions as well as bias decisions in politics, leadership, law, parental expectations and punishments on children, military rank promotion, and teacher evaluations,” the authors write. “These findings emphasize the misleading effect of attractiveness on the accuracy of first impressions and competence, which can have serious consequences in areas such as education and hiring.”

PLOS One, 2015. DOI: 10.1371/journal.pone.0148284 (About DOIs).