Who wants to play the “Inequality game?” The winner is whoever succeeds in causing a feeling of injustice (and therefore anger) in his or her opponents. Several participants tested out this rather original “game” as part of a Swiss study. The experiment aimed to better understand the cerebral mechanisms that underlie anger and the desire to punish those responsible for putting us in this state. Discover how our brain manages to control its desire for revenge…

Few studies have investigated the neuronal functions involved in disassociating angry feelings from the regulation of aggressive reactions (responses or punitive behaviors). As specified by the study’s authors, anger doesn’t always lead to punishment. Previously, experiments were conducted to highlight the neural correlates of anger and aggression. One of these consisted of alternating periods of provocation, during which participants received electrical shocks from another player, and periods during which these same participants could themselves retaliate by administering “stimulations.” But this “original” protocol (the Taylor Aggression Paradigm) wasn’t terribly helpful in discriminating the feelings of anger from the desire for revenge. To avoid this bias, researchers from the Swiss Centre for Affective Sciences and the Laboratory of Behavioral Neurology and Imaging of Cognition (University of Geneva, Switzerland) adopted a somewhat less (physically) painful protocol for the participants.

The “game of inequalities” is an interactive economic game developed by O. Klimecki-Lenz (one of the study’s co-authors) designed to first provoke a feeling of injustice and anger in participants and then offer them an opportunity for revenge. 25 men (average age = 26 years old) had the “pleasure” of taking part in this game. The game takes place in 3 stages during which a participant placed in an MRI scanner takes part in economic interactions with two other players seen in photographs. What he doesn’t know is that the behavior of his opponents is pre-programmed. One of the two is fair and will offer him mutually beneficial transactions (he’ll even send him kind messages, such as: “you’re nice”); while the other player will only look to satisfy his own interests by going against those of the participant (the unfair player will even send the participant messages specifically designed to annoy him).

During the first phase of the game, the participant chooses how he wishes to distribute the money. At this stage, the amount is often equally distributed between the two other players. During the second phase, complications arise because the participant receives unfair decisions along with provocations from the unfair player. At this point, the participant rates his feelings of anger on a scale from 0 to 10. This data was used to establish a correlation between the level of self-declared anger and the density of activity in the temporal superior lobe and amygdala (which plays a role in the processing of emotions).

In the final phase, the participant becomes the game master again and can decide to take revenge by penalizing other players. Most of the participant opted to take revenge for the injustices committed by the unfair player. But more surprisingly, 11 subjects remained unphased by the unfair player. MRI data showed that, when compared to the other participants, these subjects had greater activation in a particular area of the brain: the dorsolateral prefrontal cortex or DLPFC. This area plays an important role in the regulation of emotions. The scientists noticed that the more active this area was during the second phase of the game (provocation), the less participants were likely to take revenge on the unfair player. Conversely, the less active the area, the more likely the revenge.

O. Klimecki-Lenz notes that: “DLPFC is coordinated with the motor cortex that directs the hand that makes the choice of vengeful behavior or not.” According to the authors, the results of this research provide new insights about the functional mechanisms involved in regulating anger and inhibiting the desire for revenge. In particular, it opens up new paths in neuropsychiatry for the treatment of anger management and aggressive behavior.