THE SIMILARITY between our own and another person’s face plays an important role in how attractive we find that person and also how trustworthy.
Choosing who to trust and who to mate with is important for humans, as well as animals. It is important for genetic diversity that our mate not be too closely related to us (to limit inbreeding), explained Dr Lisa DeBruine of the University of Aberdeen.
Dr DeBruine has been using computer graphics to manipulate photographs of randomly selected people, making them look more like the participants in her study to investigate how we respond to people who look like us.
“We did one study where participants were playing a game over the internet with one of these faces that had been made to look like them or like someone else. At some point in the game, they had to decide whether or not they were going to trust the other player to make a decision,” explained Dr DeBruine. What she found is that normally in the game, participants trusted the other person 50 per cent of the time. “But when the faces were made to subtly look like them, trust increased to 73 per cent,” said Dr DeBruine. This perceived genetic relatedness should increase your propensity to trust and to co-operate with another person.
“But there are some situations in which resemblance due to genetic relatedness is not a good thing – mating being a clear example,” explained Dr DeBruine. “So we’ve also looked at attractiveness judgments of people who look like you.” Dr DeBruine used the same image manipulation to create a face that was the opposite sex but looked like the participant.
“Men saw women’s faces who looked like them and women saw men’s faces who looked like them. When they were judging them for trustworthiness, they thought these people . . . were more trustworthy than average. But when they were judging the same faces for physical attractiveness, they thought they were less attractive than average – they actually disliked people who looked like them.”