The neuropeptide oxytocin fosters romantic attraction and maternal-infant bonding, and a new study indicates that the chemical also influences how much we trust other people.
Ernst Fehr et al. gave study subjects several dollars, and asked them to decide how much of the money to give to a "trustee." Participants were told that their investment would quadruple if they gave money to the trustee, but that the trustee could decide how much, if any, of the money to give back to them.
Thirteen of 29 participants given inhaled oxytocin gave all of their money to the trustee, while only six of 29 subjects given a placebo chose to do so. When the researchers replaced the human trustee with a computer making random payoffs, this difference disappeared, indicating that oxytocin enhanced trust in other people rather than merely making the participants less risk-averse.
The researchers say, "These results concur with animal research suggesting an essential role for oxytocin as a biological basis of prosocial approach behavior."
"Oxytocin increases trust in humans," Michael Kosfeld, Markus Heinrichs, Paul J. Zak, Urs Fischbacher, and Ernst Fehr, Nature, Vol. 435, June 2, 2005, 673-6. Address: Ernst Fehr, firstname.lastname@example.org.