When a person is deemed trustworthy, we perceive that person's face to be more similar to our own, according to a new study

A team of scientists from the Department of Psychology at Royal Holloway University, found that feelings of similarity towards others extend beyond social closeness and into physical characteristics, using trust as the basis in this experiment. Researchers showed volunteers images in which varying percentages of the volunteer's face were morphed with that of one of two other people, and asked them to decide whether each photo contained more of their face or more of the others. The volunteers then took part in bargaining games with both of the other people - one in which trust was reciprocated, and in the other in which it was betrayed. After the game, the volunteers carried out the photo morph task again and it was found that participants judged the trustworthy player to be more physically similar to them than the untrustworthy one. "Recent studies show that when a person looks similar to ourselves, we automatically believe they are trustworthy. 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," said researcher Harry Farmer. The team also believes that their results could hold important implications for social relationships. "It may be that our experience of facial similarity tracks information about genetic relatedness. If so, our results suggest that evidence of trust in others also serves as a cue to kinship," said researcher Ryan McKay.