Oxytocin makes us trusting but not gullible

Originally known for its role in childbirth and lactation, oxytocin (OT) has recently proved to play a key role in social behavior. Deprived of OT, humans are unable to recognize 1,2 and to bond 3 to their peers. Inversely, once boosted with OT, people become more caring 4 , trusting 5,6,7 and generous 8. Effect-sizes on trust and generosity were sufficiently large that OT started to be perceived as a natural drug that would make people credulous 9. But could OT really impede judgment and lead individuals to trust untrustworthy peers? Here we show that oxytocin makes people trusting, but not gullible. Namely, OT did not have a trust-enhancing effect on people who interacted with seemingly unreliable peers. These results emphasize that the effect of OT is much more context-dependent than previously thought. This finding therefore invalidates some of the potential commercial or military applications of oxytocin 10. 2 " Danger breeds best on too much confidence " Pierre Corneille. Le Cid In recent times, no hormone has fascinated the general public as much as oxytocin (OT). " A dose of human kindness " , " love potion " , and " liquid trust " , are all nicknames that have been given to OT, a neuropeptide naturally secreted in the paraventricular and supraoptic nuclei. And these nicknames unquestionably have an element of truth: An increasing number of studies indicate that OT facilitates social relationships by altering both cognitions and behaviors in a pro-social way 5-8,11-14,. For instance, oxytocin facilitates the encoding and memory of social stimuli 11,13 , improves mind-reading 12 , initates maternal behavior 4 , and substantially increases trust 5-7 and generosity 8. The effect of OT on generosity 8 and trust 5,6 was so large in previous studies (i.e., participants were 80% more trusting and generous in the OT group than in placebo group) that they unwittingly conveyed the idea that OT was a natural drug that made people nice and credulous 9. This belief was then reinforced by a recent study showing that OT quickly restored trust after betrayals 6. While the press and scientists 9 alike got concerned about potential misuses of these results by politicians, armed forces and marketers, OT retailers flourished—promising clients that spraying a thin mist of it over people would make them more trusting and willing to sign on the dotted line " 15. But are these concerns warranted? Would …