Do we more easily trust people who appear similar to ourselves? Yes, say a team of English researchers, but there is more to it than that. When we find a person to be trustworthy, we begin to see that person's face as similar to our own.

“Recent studies show that when a person looks similar to ourselves, we automatically believe they are trustworthy,” Harry Farmer, a postgraduate research student at Royal Holloway, University of London, and co-author of the study, stated in a press release. “Here we show for the first time that the reverse is also true. When a person is shown to be more trustworthy, it can lead us to perceive that person as looking more similar to ourselves.”

Experimental Design

Researchers showed 59 participants (44 female, 15 male) photographs in which varying percentages of their own face had been morphed into an image of two other people. The researchers then asked the participants to decide whether the photos contained more of their own face or more of the others’ faces. Next, the participants played two trust games. In each game, a photograph of a ‘trustee’ was presented on a computer screen, and the participants were told to decide how much of a trust — a fixed amount of money — to transfer to the trustee. After making their transfer decisions, the participants viewed pre-recorded videos of the trustees stating how much money they had decided to return to the trustor.

In reality, the experimenters made all the decisions on behalf of the trustees. In one game, the ‘trust’ was always reciprocated; in the other game, the ‘trust’ was always betrayed. After the game ended, the volunteers carried out the same photo task. This time, the participants judged the trustworthy player to be more physically similar to themselves than the untrustworthy one.

“Our results show how our perceptions of similarity between us and others extend beyond objective physical characteristics, into the specific nature of social interactions that we have,” lead author Professor Manos Tsakiris, of the Department of Psychology at Royal Holloway, University of London, stated in a press release. The team’s work may have important implications in the coming wave of commercial use of facial recognition software.

Facial Recognition Software

In a recent Ted Talk, Alessandro Acquisti describes proposed uses for facial recognition software, including interactive ads. In the case of a 2012 launch in London, billboard ads scanned passersby, judged their gender, and then tailored content to the individual. Although this example was rather crude — the content was based on gender alone and so showed either a female ad or a male ad — the technology behind it will eventually become more refined. Soon, to inspire ‘trust,’ an ad may reflect back faces appropriately similar to our own. Or, just as the researchers did in the above experiment, future advertising software could simply morph features of our own faces into those of recognizable celebrities. Welcome to the echo chamber!

Source: Farmer H, McKay R, Tsakiris M. Trust in Me: Trustworthy Others Are Seen as More Physically Similar to the Self. Psychological Science. 2013.