Whom we trust and who we don’t? The answer is conditioning

The latest research on this age old question has pointed the answer towards Pavlovian conditioning. Our trust in strangers is dependent on their resemblance to others we’ve previously known. Strangers resembling past individuals known to be trustworthy are trusted more; by contrast, those similar to others known to be untrustworthy are trusted less. This premise is the outcome of research conducted by a team of researchers lead by Oriel FeldmanHall at the New York University.

Researchers studying this concept conducted a series of experiments centring on a trust game in which participants make a series of decisions about their partners’ trustworthiness — in this case, deciding whether to entrust their money with three different players who were represented by facial images. Here, the subjects knew that any money they invested would be multiplied four times and that the other player could then either share the money back with the subject (reciprocate) or keep the money for himself (defect). Each player was highly trustworthy (reciprocated 93 percent of the time), somewhat trustworthy (reciprocated 60 percent of the time), or not at all trustworthy (reciprocated 7 percent of the time).

In a second task, the same subjects were asked to select new partners for another game. However, unbeknownst to the subjects, the face of each potential new partner was morphed, to varying degrees, with one of the three original players so the new partners bore some physical resemblance to the previous ones.

Even though the subjects were not consciously aware that the strangers (i.e., the new partners) resembled those they previously encountered, subjects consistently preferred to play with strangers who resembled the original player they previously learned was trustworthy and avoided playing with strangers resembling the earlier untrustworthy player. Moreover, these decisions to trust or distrust strangers uncovered an interesting and sophisticated gradient: trust steadily increased the more the stranger looked like the trustworthy partner from the previous experiment and steadily decreased the more the stranger looked like the untrustworthy one.

In a subsequent experiment, the scientists examined the brain activity of the subjects as they made these decisions. Here they found that when deciding whether or not the strangers could be trusted, the subjects’ brains tapped the same neurological regions that were involved when learning about the partner in the first task, including the amygdala — a region that plays a large role in emotional learning. The greater the similarity in neural activity between initially learning about an untrustworthy player and deciding to trust a stranger, the more subjects refused to trust the stranger.

This finding points to the highly adaptive nature of the brain as it shows we make moral assessments of strangers drawn from previous learning experiences.

Source: Proceedings of the National Academy of Sciences