Why do strangers trust me

Social behavior: when we trust strangers

Whether we spontaneously trust someone depends on our experience with similar-looking people. As a team led by Oriel FeldmanHall from Brown University reports in the journal Proceedings of the National Academy of Sciences, it suffices if there is a slight resemblance to someone who has previously taken advantage of us: we are already more prone to distrust.

In a series of experiments, the neuroscientist and her colleagues repeatedly had test subjects invest money. The stake basically quadrupled; however, an unknown player was allowed to dispose of it, either dividing the sum fairly or keeping it entirely to himself. The test subjects got to know three types of play partner: one behaved cooperatively in 93 percent of the cases, one in 60 percent and one in 7 percent of the cases. The test subjects only ever saw one photo of the alleged fellow player on a screen.

This article is included in Spectrum Compact, A Question of Trust

The good as well as the bad experiences left their mark. When the test subjects were asked to choose new game partners for the second game round on the basis of photos, they more often chose those who resembled the most cooperative players in the first round. A distant resemblance was enough to influence the preference. The test subjects were not aware of this.

By varying the degree of similarity between the images, the researchers were able to show that the subjects' preferences for new players changed accordingly. As was also shown by recordings of brain activity during play and when choosing a partner, it was above all the emotion-processing amygdalae that were active in both situations.

When making decisions, the brain orientates itself on past experiences, explain the scientists. FeldmanHall compares the learning processes with those of the Pavlovian dog, who is fed again and again when a bell rings, until his mouth watered at the sound of the bell alone. According to this, people would base their trust in strangers, at least in part, on the simplest learning principle: classic conditioning.