Feeling overwhelmed and unable to think after several hours of demanding cognitive tasks can wear out areas of the brain and cause us to act more aggressively.
- After intense intellectual activity, tired people show the emergence of zones with typical sleep waves in some areas of the frontal cortex, which were completely absent in others.
- This results in an increased propensity to perform aggressive acts in a socially relevant choice context.
- “These data have important implications for many everyday situations, including economic transactions and legal agreements,” according to the authors.
Weariness, inefficiency, exhaustion… These are the words used after intense intellectual activity. When a certain degree of mental fatigue sets in, our behavior may change, more specifically we may act in a hostile manner. This is what researchers in neuroscience and economics from the IMT School of Advanced Studies Lucca (Italy) recently observed. To reach this conclusion, they conducted a study, the results of which were published in the journal Proceedings of the National Academy of Sciences (PNAS).
Mental fatigue leads to increased sleep-like brain activity and aggressive actions
As part of the research, the team recruited 44 adults who completed cognitive tasks for an hour instead of 15 minutes. Next, participants played economic games that required varying degrees of aggression and cooperation, including the game of “hawk and dove.” In this game, limited resources must be shared in a hostile environment situation, with people given the choice between collaborating or engaging in authoritarian behavior, which can result in the loss of resources for both parties. Throughout the intervention, their brain activity was analyzed using an electroencephalogram (EEG).
According to the results, compared to a control group not subjected to prolonged mental fatigue, the volunteers who performed cognitive tasks and played economic games were found to be less cooperative and more hostile. More specifically, the rate of peaceful cooperation increased from 86% in the group “without fatigue” at 41% in the mentally exhausted group. Such behavioral changes are linked to a phenomenon, called “local sleep”, that the authors identified. The latter occurs when certain brain areas of an awake person begin to show on the electroencephalogram typical neuronal activity seen during sleep, namely delta waves. “The local appearance of slow sleep-like waves may lead to disengagement of frontal areas and explain the reduced capacity of individuals to exercise effective self-control,” can we read in the works.
Mental fatigue: “important implications for many situations in daily life”
“Overall, these data have important implications for many everyday situations, including economic transactions and legal agreements, because they demonstrate that when the brain is ‘tired,’ we can make choices that will even against our own interests. In fact, this is what people do in most criminal acts as well.concluded Pietro Pietrini, who participated in the study.
