Such situations are an everyday reality for members of the Special Intervention Service (DSI) of the police and defence forces. DSI operators are called on to arrest armed and dangerous individuals, for example, or suspects of terrorism or serious violence. They also take part in high-risk operations involving explosives or heavy firearms. This can cause stress and anxiety, disrupting decision-making processes and potentially leading to long-term mental-health disorders. The Netherlands Police asked the Faculty of Psychology and Neuroscience to study whether neurofeedback can be used to increase the psychological resilience of DSI recruits—experienced military personnel who have previously worked in conflict zones.

The study involved two neurofeedback paradigms, Andreas Bressler explains. The first model focused on improving emotion regulation in dangerous or life-threatening situations. “For members of these units, being able to control their emotions and stay calm is often a matter of life and death.” The second paradigm was aimed at maintaining focus in high-performance situations. “These units are often called up in an emergency, but then have to sit through long periods of inactivity. It’s important for them to recognise the moment when their focus slips.” Both paradigms had previously proved successful in clinical populations. “Our study was the first to test these neurofeedback techniques in people operating in high-performance situations.”

Threatening images

After a pre-test consisting of a questionnaire on negative emotions and an assessment of threatening images, the experimental group participated in six sessions involving specific tasks. For example, they were instructed to respond to an image of an opponent wielding a firearm. Functional MRI (fMRI) scans were used to identify which areas of the brain lit up during certain sensations and actions. Neural activity decreased if a participant managed to downregulate his emotions (all of the test subjects were male). As a reward, the image would shrink. Conversely, if brain activity increased, the image grew larger and thus more intense, meaning the participant had to work even harder to calm down. Bressler: “We wanted to find out if participants could successfully downregulate their emotions and how they could use this strategy in their work.”

During the attention tasks, participants were presented with an image containing faces and scenes mixed together. They were instructed to focus on the faces, after which the composition of the image changed. “If they managed to keep their attention on the faces, we could see this in their brain activity and rewarded them by making the faces more salient. If they got distracted, we made the faces less salient to alert participants to the fact that their attention was slipping and they had to work harder to maintain focus.”