Sense of obligation leads to trusting strangers, study says

Trusting a stranger may have more to do with feeling morally obligated to show respect for someone else's character than actually believing the person is trustworthy, according to new research published by the American Psychological Association.

"Trust is crucial not just for established relationships, it's also especially vital between strangers within social groups who have no responsibility toward each other outside of a single, transitory interaction. eBay or farmers' markets couldn't exist without trust among strangers," said lead author David Dunning, PhD, of Cornell University. "We wanted to examine why people, even those with low expectations of others, tend to trust total strangers more often than not.

Theories that people are inclined to trust others because they feel it's the social norm or they expect to gain something don't fully explain the abundance of trust among strangers, according to the study, published in APA's Journal of Personality and Social Psychology. "Our findings reveal that people trust others because they feel it's their duty or moral responsibility," Dunning said.

Researchers conducted six experiments involving 645 university students, 311 from Cornell and 334 from Cologne University in Germany. Across four of the experiments that used a behavioral test known as the "trust game," a total of 62 percent of participants trusted by giving money to a stranger who could keep it or give back a larger amount than he or she had been given. If these participants' tolerance for risk and expectations of their peers had determined their decisions, only 20 percent would have accepted the gamble, based on answers to questions administered at the beginning of the experiments.

The study used variations of the trust game, which involves two people who don't know each other. One participant begins with a small amount of money, such as $5. First, that person is asked whether he wishes to keep the money or give it to a stranger, who is the second participant. The first person is told that if he gives the money away, it will be increased by a certain factor, such as by four, resulting in $20. The second participant can keep the entire $20 or give $10 back to the first participant. Both players know the rules of the game and they remain anonymous to each other following the study.

One experiment randomly assigned participants either to the trust game or a coin-flip game, in which one participant was told that if he or she handed over the $5, the other participant would then flip a coin to determine whether to return $10. Sixty-seven percent of students in the trust game gave their money to the second participant compared with 44 percent in in the coin-flip game. "People felt more strongly that they should give the money when a reward depended on the judgment of the other person rather than a coin flip," Dunning said. "This was the case even though the same participants reported earlier that they thought there was only a 37 percent chance they would get any money back in the trust game, compared to the 50 percent chance of return with a coin-flip."

Another experiment gave participants three options: keep the $5, give away the $5 and trust the other person to share, or give the $5 to the other person with the understanding that she would flip a coin to determine who would get the money. The majority of students (54 percent) opted to trust the other participant to share, while 24 percent kept the money and 22 percent had the other participant flip the coin.

"Trusting others is what people think they should do, and emotions such as anxiety or guilt associated with not fulfilling a social duty or responsibility may account for much of the excessive trust observed between strangers every day," Dunning said.