Last updated February 13, 2018 at 4:40 pm
We are conditioned to a Pavlovian response by people’s looks. Nick Carne explains.
If you’re having trouble making new friends, it may not be your fault. Chances are your doppelgänger has a chequered past.
Psychology research from New York University suggests that 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.
The resemblance doesn’t have to be that great or even be obvious to the observer. Our brains deploy a learning mechanism in which moral information encoded from past experiences guides future choices.
How social decision-making unfolds
“Like Pavlov’s dog, who, despite being conditioned on a single bell, continues to salivate to bells that have similar tones, we use information about a person’s moral character, in this case whether they can be trusted, as a basic Pavlovian learning mechanism in order to make judgments about strangers,” says lead author Oriel FeldmanHall.
While scientists have a pretty good understanding of how social decision-making unfolds in repeated one-on-one interactions it has been less clear how the brain functions in making similar decisions when interacting with strangers.
To explore this, the researchers conducted a series of experiments using a game in which participants had to decide whether to entrust their money with three different players represented by facial images.
They knew that any money they invested would be multiplied four times and that the other player could then either share the money back with them (reciprocate) or keep the money (defect).
Each player was highly trustworthy (reciprocated 93 per cent of the time), somewhat trustworthy (60 per cent) or not at all trustworthy (7 per cent).
Why do some people look trustworthy?
In a second task, the same subjects were asked to select new partners for another game. However, unbeknown to them, the face of each potential new partner was morphed, to varying degrees, with one of the three original players, so there was some physical resemblance.
Despite not being consciously aware of this, subjects consistently preferred to play with strangers who resembled the original player they previously learned was trustworthy and avoided those resembling the untrustworthy ones.
And an interesting and sophisticated gradient was revealed: trust steadily increased the more the stranger looked like the trustworthy partner and steadily decreased the more they looked like the untrustworthy one.
In a subsequent experiment, the researchers found that when deciding whether or not a stranger could be trusted the subject brain-tapped the same neurological regions that were involved when learning about the partner in the first task, including the amygdala – 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.
The paper recently published by Proceedings of the National Academy of Sciences.