Trust and Testosterone

The latest issue of PNAS has this study which suggests that testosterone decreases trust in socially naïve humans. Here is the abstract:

Trust plays an important role in the formation and maintenance of human social relationships. But trusting others is associated with a cost, given the prevalence of cheaters and deceivers in human society. Recent research has shown that the peptide hormone oxytocin increases trust in humans. However, oxytocin also makes individuals susceptible to betrayal, because under influence of oxytocin, subjects perseverate in giving trust to others they know are untrustworthy. Testosterone, a steroid hormone associated with competition and dominance, is often viewed as an inhibitor of sociality, and may have antagonistic properties with oxytocin. The following experiment tests this possibility in a placebo-controlled, within-subjects design involving the administration of testosterone to 24 female subjects. We show that compared with the placebo, testosterone significantly decreases interpersonal trust, and, as further analyses established, this effect is determined by those who give trust easily. We suggest that testosterone adaptively increases social vigilance in these trusting individuals to better prepare them for competition over status and valued resources. In conclusion, our data provide unique insights into the hormonal regulation of human sociality by showing that testosterone downregulates interpersonal trust in an adaptive manner.

And BBC News has the scoop on the study here. A sample:

Testosterone reduced interpersonal trust, say the researchers, "but only in subjects who were generally trusting, and therefore more at risk for deceit".

Whereas in some mammals, testosterone is confined to motivating aggression in competition for status and resources, "in humans the hormone seems to motivate for rational decision-making, social scrutiny, and cleverness, the apparent tools for success in a modern society," Jack van Honk and colleagues explain.

Dr Daryl O'Connor, a health psychologist from the University of Leeds, says these findings are broadly consistent with previous research which showed that testosterone injections in men influenced aspects of their spatial and verbal abilities.

He said: "There is growing evidence to suggest that testosterone has activational as well as organisational effects in men and women.

"It is possible that testosterone can activate changes in the way we perceive and think about aspects of the world," he said.

"However, it is important to remember that hormones never act in isolation and do not account for behaviour on their own."

Cheers,
Colin