An experimental study in China has found that administering a single dose of testosterone gel to healthy males improved how quickly they learned to perform prosocial tasks compared to the group that received placebo. The study was published in Biological Psychology.
Testosterone is a major sex hormone in males. It is produced mainly in the testes, but also in the cortex of the adrenal gland. It plays a key role in the development of male sexual organs, but also produces a number of other effects on the body. In puberty, it leads to the appearance of facial and pubic hair, to increases in muscle and bone size and strength, and deepening of the voice. Testosterone plays an important role in regulating sex drive, but also contributes to balding in later years of life.
Studies have linked higher testosterone levels to increased aggression in animals. The link between testosterone and aggression in humans is less clear. A meta-analysis of studies on humans reported a positive association between testosterone levels and aggression, but the magnitude of that association is practically negligible.
Recent studies have indicated that testosterone might also induce prosocial behavior, such as making people more prone to offer fair bargains or cooperate better with others during competitions. To explain this link, scientists have proposed the so-called “social status hypothesis” that suggests that testosterone promotes behaviors that are appropriate to achieve and maintain social status. Thus, the effects of testosterone on behavior would depend on the context.
Study author Xin Wang and his colleagues wanted to test the social status hypothesis of effects of testosterone. They reasoned that, if this hypothesis is correct, participants who were given testosterone would increase their rate of learning for a task that increases their social status. To test this, these researchers devised an experiment.
Participants were 120 healthy males. Their mean age was 21 years. They were instructed to abstain from drinking alcohol, caffeine and from smoking for 24 hours before the testing session. They were randomly divided into two groups.
One group had testosterone gel applied to their shoulders and upper arms at the start of the experiment by an assistant. A placebo (a similarly looking hydroalcoholic gel without testosterone) was applied on participants from the other group. Neither participants nor the assistant applying the gel knew which gel they were applying.
Participants completed a series of prosocial learning tasks. In the scope of these tasks, participants were asked to choose between one of two symbols. One of the symbols had a high probability of a reward and the other had a low probability of a reward. The learning consisted in participants recognizing, through trial and error, which symbol is more often associated with the reward and starting to prefer that symbol.
There were three types of test situations. In the first one, participants were told that they will receive the rewards they win. In the second situation, rewards would go to another person, while in the third situation, rewards would not go to anyone (control).
Results showed that the group that received the testosterone gel learned faster in all three types of situations. Participants in the placebo group learned faster in situations when they were expecting to receive the rewards themselves compared to situations when they were earning the rewards for another person or for no one. However, participants in the testosterone group learned equally quickly when they were earning rewards for themselves and when they were earning them for another.
In the testosterone group, learning was faster in situations when they were earning rewards for themselves and when they were earning for another person, compared to the situation when no one would receive the rewards (earning rewards for the computer). In the placebo group, learning was faster when participants earned rewards for themselves compared to earning them for no one. There was no difference in learning speed in the placebo group between situations when another would receive the reward and when no one would receive it.
“In summary, by using exogenous testosterone administration and prosocial learning task, we found that testosterone could facilitate the prosocial behavior when there was no conflict between self- and other interests. Moreover, testosterone also enhanced the reward sensitivity, highlighting the role of testosterone in reward processing and decision-making,” the study authors concluded.
The study provides a valuable contribution to scientific knowledge about the effects of testosterone on male behavior. However, it should be taken into account that the sample consisted exclusively of young males. Results on males of different age might not be the same. Additionally, researchers focused solely on testosterone, while studies have shown that its effects on behavior depend on interactions with other hormones.
The study, “Can testosterone modulate prosocial learning in healthy males? A double-blind, placebo-controlled, testosterone administration study”, was authored by Xin Wang, Jiajun Liao, Yu Nan, Jie Hu, and Yin Wu.