Looks influence our decisions to trust others even when we know their reputation

Investment decisions matter, for both organisations and individuals, no doubt about this. But how do organisations and individuals decide if someone can be trusted with their money? What factors do we use for making such decisions?

WBS Research Fellow Dr Chris Olivola and WBS Professor Nick Chater, together with colleagues at University College London and Dartmouth College, USA, carried out a series of experiments to see if people made decisions to trust others based on their faces.

Their findings, published recently in the PLoS One journal, point to the astonishing fact that people, even when they are given negative information about a person's reputation, are still likely to entrust their money to this person if his or her face is generally perceived as trustworthy.

The team used a computer model developed by researchers at Princeton University to modify the apparent trustworthiness of faces, by altering their shape. These high- and low-trustworthy-looking faces were then used in a series of trust games with 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 reciprocate their trust by returning more than the invested amount.

The researchers found that participants invested 42% more, on average, in the trustworthy-looking faces. In a second experiment, the researchers gave the volunteers information about whether the trustees had good or bad histories. Even with this inside information, the average amount invested in those who looked 'trustworthy' was 6% higher.

Dr Chris Olivola said, "What is interesting is that the face matters at all when the volunteers have this background information about a trustee's tendency to reciprocate trust. Trustees with good and bad histories benefitted equally from trustworthy-looking facial features. 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."

He concludes, "It seems we are still willing to go with our own instincts about whether we think someone looks as though we can trust them."

Further information
'Unfakeable Facial Configurations Affect Strategic Choices in Trust Games with or without Information about Past Behavior', Constantin Rezlescu, Brad Duchaine, Christopher Y Olivola, Nick Chater. PLoS ONE, 7 (3):e34293. Click on the PDF link below to access this article.

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