Testosterone administration increases the sensitivity to negative feedback following risky choices in men, according to the results of a new double-blind, placebo-controlled, randomized trial. The study has been published in the scientific journal Biological Psychology.
“There have been both correlational and experimental studies to suggest that testosterone is associated with risk-taking, although the evidence is mixed,” explained lead researcher Oshin Vartanian, a scientist working at Defence Research and Development Canada, a special operating agency of Canada’s Department of National Defence.
“Earlier, we had conducted an fMRI study which had shown that when it comes to making risky choices, people are more risk averse when they make gambles involving human lives than cash (Vartanian et al., 2011). We had attributed this difference to the greater value placed on human lives than cash.”
“In the present experiment (which was part of a larger registered clinical trial) we were interested to see whether the administration of exogenous testosterone would impact people’s propensity to make risky choices, and whether the effect would be stronger for cash than lives because people appear to have a lower threshold for making risky choices in the former context.”
The data collected for this study occurred as part of a larger study examining the impact of testosterone replacement on muscle mass and physical performance in healthy young men while they experienced a prolonged energy deficit. The study included 50 healthy adult males who underwent a severe exercise-and-diet-induced energy deficit for 28 days, during which either testosterone (200 mg per week) or placebo (sesame seed oil) was administered.
The participants completed a gambling task in a functional magnetic resonance imaging scanner prior to, during, and after the 28 days. The gambling task involved the participants repeatedly choosing between a series of two options: One option had a certain outcome and the other had an uncertain outcome. The outcomes involved hypothetical human lives or cash. After selecting one of the options, the participants received feedback on their choice.
Testosterone did not appear to influence risky decision-making in general. However, men who received testosterone were more likely to select the certain outcome following negative feedback on a risky choice compared to the control group.
“Our results did not support our prediction that testosterone promotes risk-taking behavior, further weakening the evidence base for this idea in the literature,” Vartanian told PsyPost. “What testosterone did instead was make participants more sensitive to the outcomes of their risky choices. Specifically, regardless of whether the context was lives or cash, the testosterone group was more likely than the placebo group to select the sure option over the risky option immediately following negative feedback on a risky choice.”
“Despite the mixed nature of earlier evidence regarding the relationship between testosterone and risk-taking, we were nevertheless surprised not to observe an effect on risky choice in the present experiment,” Vartanian added. “Interestingly, a number of recent large-scale experimental studies and meta-analyses have reached a similar conclusion, forcing us to revisit our assumptions about the nature of this long-held assumption.”
In the gambling task, outcomes were presented both in terms of gains and in terms of losses. Previous research has found that people are less likely to make risky choices when outcomes are presented in terms of gains, but are more likely to make risky choices when outcomes are presented in terms of losses — even when the actual outcome is the same. This phenomenon is known as the reflection effect.
The researchers observed that the strength of this effect was associated with different patterns of brain activity.
“There were large individual differences in the propensity to make risky choices (in relation to whether the gamble represented gains or losses), which in turn was correlated with variation in brain function in the dorsal thalamus — a region that processes emotion, reward and risk,” Vartanian explained. “More work is needed to determine exactly why it is that this specific region is associated with individual differences in making risky choices involving both cash and lives.”
But the study includes two important caveats. “All of our data were collected from males, and we know that there are hormonal differences between the sexes. As such, it is unclear whether a similar picture would emerge in females,” Vartanian noted.
Additionally, the administration of testosterone in the current study was meant to return plasma testosterone to near-normal levels among participants in the experimental group.
“Our data were collected against the backdrop of severe energy deficit, and because energy deficit is associated with reduction in circulating testosterone levels, our administration of exogenous testosterone should be viewed as a restorative intervention,” Vartanian explained. “As such, whether the administration of exogenous testosterone above normal levels would impact risky choice as measured by our gambling task remains unknown.”
The study, “Effect of exogenous testosterone in the context of energy deficit on risky choice: Behavioural and neural evidence from males“, was authored by Oshin Vartanian, Timothy K. Lam, David R. Mandel, Sidney Ann Saint, Gorka Navarrete, Owen T. Carmichael, Kori Murray, Sreekrishna R. Pillai, Preetham Shankapal, John Caldwell, Claire E. Berryman, J. Philip Karl, Melissa Harris, Jennifer C. Rood, Stefan M. Pasiakos, Emma Rice, Matthew Duncan, and Harris R. Lieberman.
