Who do you trust?

Have you ever let a stranger borrow your cell phone? Or asked someone to watch your belongings?

We’ve all trusted a stranger from time to time, but is there a reason why we trust some strangers and not others?

A recent study found that people are more likely to trust a stranger if the stranger resembles an individual who was known to be trustworthy in the past. Likewise, strangers who resemble an individual who was not trustworthy in the past are less likely to be trusted.

“We make decisions about a stranger’s reputation without any direct or explicit information about them based on their similarity to others we’ve encountered, even when we’re unaware of this resemblance,” study author Elizabeth Phelps said in a press release.

The study consisted of a trust game where subjects had to entrust their money with a partner they chose from a facial image. Each image was labeled as someone who was either highly trustworthy, somewhat trustworthy or not at all trustworthy.

In the next task, the same subjects were asked to select new partners for a different game.

Subjects consistently chose to play with a stranger who resembled the original player who they learned was trustworthy and avoided playing with a stranger who resembled the player that they learned was untrustworthy.

“Our study reveals that strangers are distrusted even when they only minimally resemble someone previously associated with immoral behavior,” study co-author Oriel FeldmanHall said in the release. “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.”

“Trust is an extremely important part of all relationships in our lives, and the level of trust will oftentimes determine our level of investment in interacting with a specific person,” says Dr. Kevin Krippner, an Advocate Medical Group psychologist in Bloomington, Ill.

“Trust is usually created when people use their prior experience and interactions with another person to guide the amount of trust they put in the current and future relationship.”

To alter our unconscious decision making, there are other ways to determine if we can trust a stranger rather than just judging their appearance.

“It is important to try and recognize our tendency to judge others and to try and keep this tendency to a minimum,” says Dr. Krippner.

“Awareness is very important.  If you want to change this habit, try being more aware of your immediate reactions when you see others and begin to judge. Keep in mind the old adage that ‘you can’t judge a book by its cover’, and try to honor that wisdom.”