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The Neurobiology of Trust

Authors

  • PAUL J. ZAK,

    Corresponding author
    1. Center for Neuroeconomics Studies, Claremont Graduate University, Claremont, California 91711-6167, USA
    2. Department of Neurology, Loma Linda University, Loma Linda, California, USA
    3. Gruter Institute for Law and Behavioral Research, Portola Valley, California, USA
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  • ROBERT KURZBAN,

    1. Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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  • WILLIAM T. MATZNER

    1. Center for Neuroeconomics Studies, Claremont Graduate University, Claremont, California 91711-6167, USA
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Address for correspondence: Center for Neuroeconomics Studies, Claremont Graduate University, Claremont, CA 91711-6165. Voice: 909-621-8788; fax: 909-621-8460. paul.zak@cgu.edu

Abstract

Abstract: This is the first report that endogenous oxytocin in humans is related to social behaviors, which is consistent with a large animal literature. Subjects are put into a social dilemma in which absent communication, cooperative behavior can benefit both parties randomly assigned to a dyad. The dilemma arises because one participant must make a monetary sacrifice to signal the degree of trust in the other before the other's behavioral response is known. We show that receipt of a signal of trust is associated with a higher level of peripheral oxytocin than that in subjects receiving a random monetary transfer of the same average amount. Oxytocin levels were also related to trustworthy behavior (sharing a greater proportion of the monetary gains). We conclude that oxytocin may be part of the human physiology that motivates cooperation.

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