Looks Overshadow Reputation When Deciding Who To Trust

When faced with a decision of who to trust with money, people will often choose the face that looks the most trustworthy, shunning those who they deem look sketchy.

Interestingly, a new study shows that the person's track record doesn't impact this choice — people will still choose the most trustworthy face, even if they are told that the owner of that face has a bad reputation.

"The temptation to judge strangers by their faces is hard to resist. Trustworthiness is one of the most important traits for social and economic interactions and our study examines whether people take potentially costly actions in line with their face-based trustworthiness judgments," study researcher Chris Olivola, of the University of Warwick in the United Kingdom, said in a statement. "It seems we are still willing to go with our own instincts about whether we think someone looks like we can trust them."

How trustworthy a person looks is determined by the width of their faces, a study published in March of 2010 in the journal Psychological Science showed. Those with wider faces are perceived as less trustworthy, while people with narrower faces are seen as more trustworthy. This was also backed up by more recent work, published in July of 2011, which indicates that these wide-faced people act unethical.

Face width is something called an "unfakeable" feature, since without plastic surgery it's very difficult to change the shape of the face to look more trustworthy. The latest research, detailed March 28 in the journal PLoS One, used a computer algorithm to create a set of 20 pairs of faces made wider (untrustworthy) or thinner (trustworthy). These 40 faces were then used in a series of trust games with human participants.

Each volunteer was given a sum of money and told they could invest any part of the amount in a trustee whose face appeared on the screen. Any amount they invested would be tripled and volunteers were told it was then up to the trustee to decide how much to send back to them. Thus participants had an incentive to invest only in trustees who could be expected to return more than the invested amount.

The researchers found that 13 out of 15 participants invested more, on average, in the trustworthy looking faces. In a second experiment, the volunteers played the same game, but were told whether the trustees had good or bad histories. Even with this inside information, the average amount invested in those who looked trustworthy was 6 percent higher.

"Trustees with good and bad histories benefitted equally from trustworthy-looking facial features," Olivola said.