Researchers including lead author David Dunning, PhD, of Cornell University, 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.
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 dollars. 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 dollars. The second participant can keep the entire 20 dollars or give 10 dollars 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 dollars, the other participant would then flip a coin to determine whether to return 10 dollars. Sixty-seven percent of students in the trust game gave their money to the second participant compared with 44 percent 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 dollars, give away the 5 dollars and trust the other person to share, or give the 5 dollars 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.
The study has been published in APA's Journal of Personality and Social Psychology.