Researchers from the University of Birmingham and the University of Oxford have shown that the will to work is not static and depends on fluctuating fatigue rates. The research team conducted a study to look at the influence of fatigue on a person’s decision to exert themselves and found that people were less likely to work and even exert themselves for a reward when they were tired.
Fatigue or feeling tired from doing strenuous tasks is something we all experience on a daily basis, it makes us lose motivation and take a break. Although scientists understand the mechanisms the brain uses to decide whether a particular task is worthwhile, the influence of fatigue on this process is not yet well understood.
Interestingly, the researchers found that there were two different types of fatigue that were detected in different parts of the brain. First, fatigue is felt like a temporary feeling that can be overcome after a short break, a second long-term feeling builds up that prevents people from wanting to work and does not go away with short breaks.
“We found that people’s willingness to make an effort fluctuated from moment to moment, but gradually decreased over time as they repeated a task, “says Tanja Muller, lead author of the study from Oxford University. “Such changes in motivation to work seem to be related to fatigue and sometimes lead to our decision not to continue.”
Participants completed more than 200 tests, each of which asked if they would prefer to” work”, which meant a grip strength machine to push and get the highest rewards offered, or to rest and earn only a small reward. A mathematical model to predict how tired a person would be at any point in the experiment and how much that fatigue their decisions, too work or rest affected the brain that was consistent with the model’s predictions.
They found areas of the front of the brain cortex that were predicted to fluctuate with activity, while an area called the ventral striatum indicated how much fatigue was affecting people’s motivation to keep working.