Studies suggest that the more decisions you make over the course of a day, the worse your decisions become—a phenomenon known as “decision fatigue.” In a now-famous study(1), researchers examined decisions made by parole board judges. These are professional decision makers whose job is to hear appeals from felons, confer amongst themselves, and come to an objective decision about whether to release the felon from prison.
The researchers wanted to know whether there was any correlation between the rulings and the time of day at which they occurred. To find out, they analyzed 1,112 judicial rulings from a period of 10 months.
The analysis revealed that at the beginning of each day, the judges granted parole to an average of 65 percent of offenders. But as they made more and more rulings over the course of a morning, the judges granted parole to fewer and fewer inmates, until the average percentage of favorable rulings dropped to nearly zero.
The act of making decisions, it seems, left the judges fatigued. And since granting release to an inmate requires carefully weighing the risk that they’ll commit another crime, the easiest thing for a weary brain to do is to do nothing, simply denying the inmate’s application and letting them remain in prison.
But after the judges ate lunch and returned to court rested and rejuvenated, their likelihood of granting favorable rulings surged back up to 65 percent. It’s not clear whether the judges’ renewed vigor was the result of eating food or just taking a break, but the researchers concluded that it was decision making, not just the passage of time, that had fatigued them.
In related research(2), scientists investigated how decision fatigue affects consumer choices. Levav wanted to know how the fatiguing task of configuring the endless options on a new car would affect what car buyers chose. So he worked with car dealerships in Germany to manipulate the order in which a car’s configuration options were presented. When buyers had to decide whether they wanted expensive extras like rustproofing, was that decision presented to them before or after they’d had to page through 56 different paint shades to decide what color they wanted? The results showed that buyers made careful choices at the beginning, but as they fatigued, they became more and more likely to just settle for the default option, even if it was more expensive.
Other research supports the idea that brains tend to work better in the morning, before they’ve become fatigued by the choices of the day. Early risers tend to be more productive (N.B., this by itself doesn’t imply that late risers who get up early will become more productive).(3) Older adults have better cognitive performance and a greater ability to tune out distractions in the morning than in the afternoon.(4) And people even behave more ethically—engaging in less lying and cheating—in the morning, a phenomenon known as the “morning morality” effect.(5) Everything else being equal, it seems the best decisions are made in the morning.
1. Danziger, S., Levav, J., & Avnaim-Pesso, L. (2011). Extraneous factors in judicial decisions. Proceedings Of The National Academy Of Sciences, 108, 6889–6892.
2. Levav, J., Heitmann, M., Herrmann, A., & Iyengar, S. (2010). Order in product customization decisions: evidence from field experiments. Journal Of Political Economy, 118, 274–299.
3. Defend your research: the early bird really does get the worm. (2010). Harvard Business Review.
4. Anderson, J., Campbell, K., Amer, T., Grady, C., & Hasher, L. (2014). Timing is everything: age differences in the cognitive control network are modulated by time of day. Psychology and Aging, 29, 648–57.
5. Kouchaki, M. & Smith, I. (2013). The morning morality effect: the influence of time of day on unethical behavior. Psychological Science, 25, 95–102.