Many studies have shown that testosterone can influence levels of aggression. But there haven’t been many studies that show exactly how testosterone may cause aggressive behaviours.
The amygdala is a part of the brain associated with emotional response and it prepares our body for fight or flight. Goetz et al hypothesized that testosterone might influence the activity (or reactivity) of the amygdala, much like other research has shown serotonin does.
The study used 16 healthy young men who were tested over two days. The design was a repeated measures design as all 16 men participated in both conditions.
The researchers made sure that all the participants base-line testosterone levels were the same before the experiment began. In the treatment condition of the experiment they were given a dose of testosterone. The control condition received a placebo.
After the treatment/placebo they were placed in an fMRI scanner and their brain activity was measured while they saw images of faces expressing different emotions.
The results showed that in the increased testosterone condition the reactivity* of the amygdala was higher when participants were shown the angry face.
Critical Thinking Questions
- How might testosterone influence our behaviour?
- What are the limitations in using this study to explain aggression? (especially reactive aggression).
Goetz, Stefan M.m., Lingfei Tang, Moriah E. Thomason, Michael P. Diamond, Ahmad R. Hariri, and Justin M. Carré. “Testosterone Rapidly Increases Neural Reactivity to Threat in Healthy Men: A Novel Two-Step Pharmacological Challenge Paradigm.” Biological Psychiatry 76.4 (2014): 324-31. Web.
Read an online article about this study here.
Original study abstract.
*Reactivity: the level of activity in the brain as it reacts to a certain stimulus. In this case it means that when shown the angry faces in the fMRI machine the amygdala would have higher levels of activity than in the other condition.