“All in!” Maybe you wouldn’t have dared to make such a bold decision at the poker table had you not been surrounded by players with a taste for risk? Indeed, it appears that the love of risk may be “transmissible,” even to more cautious individuals, due to brain mechanisms that stimulate this “behavioral contagion” effect. Why do we tend to take more risks when we are in contact with those more reckless than ourselves?

To study the potentially contagious effect of risk-taking, researchers from Caltech developed a betting simulation experiment to study the behavior of 24 participants. Three types of processes were developed. The first was an "observation" process, in which participants observed the risk-taking behavior of a peer. The second involved a “prediction” process in which the participant had to predict the tendencies of a peer, without having any information about the outcome of the risk taken. In the third or “self” process, the participant was given a maximum of 4 seconds to choose between a safe but low-paying bet ($10) or a much riskier bet with the potential for a much higher gain.

What did J. O'Doherty and his colleagues observe? It turns out, the participants were much more likely to make a more risky bet in the “self” condition if they had already observed a peer taking risks. This contagious effect also works in the reverse condition: a participant observing a more conservative peer will demonstrate a similar behavior when it is his or her turn to choose. According to S. Suzuki, a postdoctoral researcher in neuroscience, by observing people that either do or don’t have a taste for risk, we in turn become more or less prone to risky behavior. This means that (personal) risk-taking behavior can be influenced by the act of observing and learning from the decisions of others.

In order to detect the potential brain areas involved in this type of risk-taking, the team of researchers used a functional MRI (fMRI). Participants’ brain activity was examined during the different phases of the experiment. J. O’Doherty’s team was able to determine that the caudate nucleus area was associated with risk evaluation. For example, a risky bet gave rise to greater activity in this brain area than a low-risk bet. In addition, the fMRI data collected in the “observe” process showed that another part of the brain, the prefrontal dorsolateral cortex, was active when participants were observing peer attitude to risk. These two brain areas work together to make the person more or less susceptible to the influence of others' risk-taking behavior.

The results of this study, published in Proceedings National Academy (PNAS), are part of a larger research framework, in which scientists are trying to determine how we can learn from others in society. According to J. O’Brien: “Ultimately, if we can understand how our brains function in social situations, this should also enable us to better understand how brain circuits can go awry, shedding light on social anxiety, autism, and other social disorders.”