Personality and hormones: Trait anxiety influences the link between testosterone and aggression

For many years, testosterone has been associated with aggressive and dominant behaviour, especially in male populations. In more recent years, researchers have focused on how individual personality differences can influence the effects of testosterone on aggression.

One such study examined trait anxiety, which can be defined as “a measure of one’s tendency to perceive situations as threatening.”

Research conducted by Rachael Norman, Benjamin Moreau, Keith Welker and Justin Carre for the journal Adaptive Human Behaviour and Physiology examined how levels of trait anxiety may be able to influence the degree to which testosterone can encourage aggressive behaviour. In two experiments, they found testosterone was associated with more aggressive behaviour during competitions, but only among men scoring relatively low in trait anxiety.

The first experiment of 80 participants from both genders used self-report methods, saliva samples, competitive gaming and reactive aggression methods to assess whether trait anxiety could be an influencing factor in the relationship between testosterone and aggression.

From the analyses of the results a positive correlation between the release of testosterone and subsequent aggressive behaviour was discovered, although this was only present in those scoring low in trait anxiety.

Interestingly, however, researchers reported that “the relationship between T reactivity and aggression is in the opposite direction for men with relatively high anxiety”.

Their second experiment of 237 participants assessed men and women separately, and assigned the participants to a condition in which they either frequently won or frequently lost

The researchers again found positive correlations between testosterone reactivity and aggression in the male sample for those with low trait anxiety, irrespective of whether the participant was on a losing or winning streak. However, these effects were not present in the female participants.

The findings demonstrate that the proposed relationship between testosterone and aggression is not as simple as first suggested, as the results appear to highlight the role of individual personality differences in this relationship.

“Here, across two studies, we found that trait anxiety moderated the relationship between T responses to competition and aggressive behavior in men,” the researchers concluded. “Specifically, T responses to competition were positively correlated with subsequent aggression, but only in men scoring relatively low on a dispositional measure of anxiety. These findings highlight the importance of considering individual difference factors when attempting to characterize neuroendocrine mechanisms underlying human aggression.”