The Neuroeconomics of Trust

24 Pages Posted: 4 Aug 2005  

Paul J. Zak

Claremont Graduate University - Center for Neuroeconomics Studies

Date Written: August 2005


The traditional view in economics is that individuals respond to incentives, but absent strong incentives to the contrary selfishness prevails. Moreover, this "greed is good" approach is deemed "rational" behavior. Nevertheless, in daily interactions and in numerous laboratory studies, a high degree of cooperative behavior prevails - even among strangers. A possible explanation for the substantial amount of "irrational" behavior observed in markets (and elsewhere) is that humans are a highly social species and to an extent value what other humans think of them. This behavior can be termed trustworthiness - cooperating when someone places trust in us. I also present the cross-country evidence for environments that produce high or low trust. A number of recent experiments from my lab have demonstrated that the neuroactive hormone oxytocin facilitates trust between strangers, and appears to induce trustworthiness. In rodents, oxytocin has been associated with maternal bonding, pro-social behaviors, and in some species long-term pair bonds, but prior to the work reviewed here, the behavioral effects of oxytocin in humans had not been studied. This chapter discusses the neurobiology of positive social behaviors and how these are facilitated by oxytocin. My experiments show that positive social signals cause oxytocin to be released by the brain, producing an unconscious attachment to a stranger. I also discuss recent research that manipulates oxytocin levels, and functional brain imaging research on trust.

Keywords: Trust, oxytocin, brain, fMRI, experiments

JEL Classification: C91, C92

Suggested Citation

Zak, Paul J., The Neuroeconomics of Trust (August 2005). Available at SSRN: or

Paul J. Zak (Contact Author)

Claremont Graduate University - Center for Neuroeconomics Studies ( email )

160 E. 10th St.
Claremont, CA 91711-6165
United States

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