Decision Fatigue: Do You Need to Give Your Brain a Break?
Posted on October 27, 2015 by Ursina Teuscher, One of Thousands of Executive Coaches on Noomii.
Making decisions is hard work for our brain, and for good reasons.
As much as we enjoy having lots of choices, it turns out making decisions is hard work. It is tiring and wears us out to a surprising extent – more so than other mental tasks.
At this point, a large body of research shows that whenever we make many decisions in a row, their quality goes down. One study in 2011 got a lot of media attention, because it looked at real parole decisions, made by experienced judges at an Israeli prison. At the beginning of the day, the judges were likely to give a favorable ruling in about 65 percent of the time. As the morning wore on, the likelihood of a criminal getting a favorable ruling steadily dropped to zero. After the lunch break, the likelihood of a favorable ruling would immediately jump back up to 65 percent. And then, as the hours moved on, the percentage of favorable rulings would fall back down to zero by the end of the day. Regardless of the crime, a prisoner was much more likely to get a favorable response if their parole hearing was scheduled either early in the morning or immediately after a food break, than if it was scheduled near the end of a long session. In other words, the outcome of a decision was highly influenced by how many decisions the judges had already made previously.
In the meantime, lots of experiments – both in the lab and with real choices in the field – have shown similar patterns. Moreover, some kinds of decisions seem to be especially taxing: namely those that involve self-control and willpower. For example, when people fended off the temptation to eat candies or cookies for a while, they were then less able to resist other temptations later on. Eating or drinking after a self-control task helps against these impairments, and sleep and rest also replenish the ability to exert self-control.
This pattern is very much in line with other things we know about impulsive behavior and self-control problems. For example, research on crime and addiction suggests that hypoglycemia and poor glucose tolerance is common among people who show impulsive, criminal or aggressive behavior. We also know that alcohol reduces glucose throughout the brain and body and likewise impairs many forms of self-control.
Interestingly, self-control tasks and decisions do indeed require and consume measurably more glucose in the blood than other mental tasks. Low or hypoglycemic levels of glucose lead to impaired decision making, poor planning, and inflexible thinking. In contrast, glucose levels don’t have that much affect on other mental tasks, such as reacting quickly to cues.
All of this begs the question: what is so special about decision-making that it can wear us out so much more than other tasks?
The answer to this is still somewhat controversial. What we do know is that self-control, planning and decision-making are all processes that involve the frontal areas of the brain — the pre-frontal cortex, to be specific. This is the most recently developed part of our brain, and it is not as essential to our survival as other areas of the brain. It makes sense that the brain functions that are more central to our survival would have first dibs on available glucose when the going gets tough, therefore not always leaving enough fuel for more advanced thinking and planning.
How can we use this knowledge in our own lives to make better decisions?
1) Eat healthy and get enough breaks, rest and sleep.
All this research certainly gives new meaning to the wisdom of not shopping on an empty stomach. It turns out hunger doesn’t only affect grocery shopping though. We should simply avoid making important decisions when we’re hungry and tired. Giving our brains a break once in a while is essential.
2) Plan ahead.
The finding that that our psychomotor abilities are not as easily impaired as our abilities for judgment and decision making suggests we will often not realize our impairment, because the very capacity (judgment!) that we would need to recognize it is the first one to be impaired. This is why planning ahead, and planning well, is so important.
3) Get into good routines.
If you build your daily decisions into healthy routines, those give you free rides. Similarly to a good plan, an established routine will allow you to do everything you want without having to make too many decisions along the way, and without having to exert so much self-control.
Selected References:
Danziger, S., Levav, J., & Avnaim-Pesso, L. (2011). Extraneous factors in judicial decisions. Proceedings of the National Academy of Sciences, 108(17), 6889–6892.
Gailliot, M. T., & Baumeister, R. F. (2007). The physiology of willpower: linking blood glucose to self-control. Personality and Social Psychology Review, 11(4), 303–327.
Hagger, M. S.; Wood, C.; Stiff, C.; Chatzisarantis, N. L. D. (2010). Ego depletion and the strength model of self-control: a meta-analysis. Psychological Bulletin, 136 (4), 495–525.
