Jill Lobbestael, Suzanne Brugman, Franziska Dambacher and Alexander Sack Jill Lobbestael, Suzanne Brugman, Franziska Dambacher and Alexander Sack Sacha Ruland

From hot sauce to tickling the brain: Measuring, predicting and lowering aggression

In Mind
Written by  Jolien Linssen Wednesday, 17 September 2014 09:43
Imagine the following situation. You have agreed to cook dinner for your mother-in-law, who has been acting rather strangely lately. “Wasn't she ignoring me the last time we visited her?”, you grumble to yourself while preparing the chilli sauce. Her behaviour has been bothering you for weeks now. The water boils. Chopping the peppers, you realise she’s been mean to the kids too. “She doesn't answer their phone calls. And she didn’t even show up at Billy’s birthday party.” You chop and chop, and while your heart beats faster, more and more peppers slip into the bowl. You're angry – and she’s going to taste it. The proof is in the sauce.

Measuring aggression is a complicated matter. This has led clinical psychologists to come up with ingenious ways to find indicators for it, one of them being the so-called hot sauce experiment. "After someone's anger is triggered, we ask them to prepare a dipping sauce for someone else. The spiciness of the sauce is then an indicator or sign of aggression", says clinical psychologist Jill Lobbestael.

As assistant professor at the Maastricht Faculty of Psychology and Neuroscience, she applied for a grant from the Netherlands Organisation for Scientific Research (NWO). The goal: to study aggression from both a cognitive and a neuroscientific perspective not only to measure, but also to predict and even lower aggressive behaviour in violent offenders.For though we might all experience feelings of anger or aggression sometimes – be it towards our boss or our mother-in-law – only for a small minority will this result in excessive behaviour.

"What makes this research innovative is the fact that it combines clinical psychological science, which is Jill’s area of expertise, and cognitive neuroscience", explains Alexander Sack, professor of Functional Brain Stimulation and Neurocognitive Psychology. "Every sort of behaviour is somehow linked to the brain eventually. In our department, we know how to measure and manipulate brain activity. The challenge is to figure out how the findings of clinical psychologists – their ideas about what aggression is and how it can be measured – can be translated into our world, which is that of the scanner."


Quite a challenge indeed. Such close collaboration between the departments of clinical psychological science and cognitive neuroscience has not been witnessed before. It is up to PhD candidates Suzanne Brugman and Franziska Dambacher to bridge the gap.

Brugman, who works alongside Lobbestael at the clinical psychology department, has mainly done research in forensic clinics. Here, the research team monitors the occurrence of violent incidents and measures aggression experimentally. “For example, by having patients participate in a competitive reaction time game", Brugman says. “The game is designed for two people: the participant and the opponent, who is in fact non-existent. The participant’s task is to push a button as soon as it turns red. If the participant is faster than the opponent and hence wins the game, he or she may ‘punish’ the opponent by sending a noise, and vice versa.”

The bottom line of the experiment: the length and loudness of the noise is an indicator of aggression, just like the spiciness of the sauce. What’s more, it allows the researchers to test whether a participant will act aggressively without first being provoked, or only after being confronted with a mean opponent who inflicts harsh punishments.

"We’re very happy that we’re able to work with behavioural measures like these", says Lobbestael. "Since many clinical patients score highly on psychopathy and antisocial personality disorders, they tend to lie a lot. Self-report questionnaires of aggression, which we used in previous studies, therefore proved to be very unreliable. In the current experiments, what we’re actually measuring is not that obvious to the participants."

Further, the behavioural measures developed by clinical psychologists can also be performed in the functional magnetic resonance imaging (fMRI) scanner that Dambacher is working with in the cognitive neuroscience department. "With the necessary modifications, we’ve been able to have participants play the reaction time game in the scanner. This allows us to see what happens in their brain while they’re playing."  


Although this may sound straightforward, mapping aggression in the brain is far from easy. "Normal brain research focuses on very simple things, because our brain is so complicated", says Sack. "Academics spend their entire careers trying to understand what happens in the visual system when we perceive a stripe, for example. And now we’re talking about being aggressive in a social situation." Therefore, a key aim has been to link the concept of aggression to a system in the brain that is already familiar. Sack: "The network we mapped during the reaction time game shows overlap with the already well-documented inhibition network in the brain." In other words: the (in)ability to inhibit behaviours and hold oneself back plays a role in aggressive behaviour. 

"This is in line with studies in social psychology showing that self-control is a strong predictor of aggression", Lobbestael continues. "We’ve also found that attention is linked to aggression. People who act aggressively are highly sensitive to negative triggers, such as insults. They also tend to misinterpret ambiguous triggers as hostile.”


Where does this leave us when it comes to predicting aggressive behaviour, or even modifying it? "It’s too early to say ‘this person has an attentional bias, so he’ll be aggressive in the next year’", Brugman says. Nonetheless, the results to date are promising. Sack: "One of our recent studies has shown that aggression in healthy males can be lowered by 'tickling' the brain using non-invasive brain stimulation. It’s a first result and we have to be cautious, but to me this is an intriguing finding. It might be a first step towards a new sort of treatment for patients."

"Of course we have to see whether we can replicate it and how long the effect would last", Dambacher adds. "The best chance to lower aggression will probably be with a set of interventions, both cognitive and neuroscientific. The strength of our team, which also includes Professor Arnoud Arntz and Teresa Schuhmann, is that it combines both worlds."


Jill Lobbestael (1980) studied Mental Health at Maastricht University, where she received her PhD in 2008. Currently, she is assistant professor at the Faculty of Psychology and Neuroscience. Lobbestael also works as a therapist. 
Alexander Sack (1972) studied psychology in Frankfurt, Germany. He received his PhD in 2003, then relocated to Maastricht University. He has been professor of Functional Brain Stimulation and Neurocognitive Psychology since 2011.
Franziska Dambacher (1986) studied psychology, theology and philosophy in Trier, Germany. She joined the Vision Awareness and Cognition group at Maastricht University in 2011.
Suzanne Brugman (1986) studied psychology in Nijmegen, where she obtained master’s degrees in clinical psychology and behavioural science. She has been working at Maastricht University since 2011. 

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