What is decision fatigue?
Decision fatigue is one phrase carrying three claims: a mechanism, a pattern and a piece of advice. Only one of the three has failed its tests.
Answer to the question
What is decision fatigue?
Decision fatigue is the idea that making many decisions in a row makes later decisions worse, lazier or more impulsive. It was popularised in 2011 and rests on ego depletion, a mechanism that large preregistered tests have not reproduced. Field studies still show decisions shifting across a session, with the causes disputed.
Key takeaways
- John Tierney's August 2011 article in The New York Times brought decision fatigue to a wide audience by joining lab experiments on self-control to a study of Israeli parole rulings and work on car and suit buyers.
- Vohs and colleagues (2008) reported that making choices impaired later self-control; their 2021 test across 36 laboratories and 3,531 participants found an effect of 0.06 standard deviations, not statistically significant.
- Danziger and colleagues (2011) analysed 1,112 parole rulings by eight judges and reported favourable rulings falling within sessions; a reply in the same journal pointed to overlooked case ordering.
- Linder and colleagues (2014) found the odds of an antibiotic prescription were about a quarter higher in the fourth hour of a clinic session than in the first, across 21,867 visits and 204 clinicians.
- Hirshleifer and colleagues (2019) reported that analyst forecast accuracy fell as the number of forecasts already issued that day rose.
Decision fatigue has a respectable pedigree and a shaky foundation, and the two are easy to confuse. The pedigree is a run of studies in which people who had made many decisions in a row went on to decide differently. The foundation is a theory of depleted mental fuel that the largest tests have not supported. John Tierney set the idea out in The New York Times, and it read as a finding about human nature, the sort of fact a reader could apply to a Monday morning, a shopping trip or a boardroom agenda without further thought.
Tierney's article gathered lab experiments on self-control, a study of Israeli parole rulings and research on people configuring computers, cars and suits, and it mixed three different kinds of claim.
One is about mechanism: making choices uses up a shared resource that also powers self-control. One is about pattern: decisions made late in a long run of them differ from decisions made early, often by taking the easier or more habitual route. One is advice: cut the number of choices you face so that you keep something in reserve.
The pattern could be real while the mechanism is wrong, and the advice could be sound for reasons unrelated to any fuel tank, so asking whether decision fatigue is real means asking three questions at once.
The Mechanism Lost Its Footing
Roy Baumeister and colleagues proposed in 1998 that self-control draws on a limited resource, and called the resulting state ego depletion. Kathleen Vohs and colleagues extended the idea to choosing in a 2008 paper, reporting that making choices impaired later self-control. Daniel Kahneman, in Thinking, Fast and Slow, treats depletion as an established finding and discusses the parole study as a sign that fatigue and hunger probably both play a part in how judges rule. That was the state of belief when Tierney's article of August 2011 brought decision fatigue into popular use.
The tests that came later were harder on the idea. In 2021 a preregistered study run across 36 laboratories with 3,531 participants found an effect of 0.06 standard deviations, which was not statistically significant, and a Bayesian analysis favoured the null by about four to one. Vohs was among the authors of that test. The result does not say that tiredness never affects judgement. It says the depletion mechanism behind decision fatigue has not held up under the most careful attempt to reproduce it, a story told in full in Willpower Is Not a Fuel Tank.
Real Decisions Drift, Cause Unclear
The pattern claim rests on records of real decisions, and here the picture is less settled. Shai Danziger and colleagues analysed 1,112 parole rulings by eight Israeli judges and reported that favourable rulings fell from about 65 per cent to nearly zero within a session, then rose after a break. A reply in the same journal pointed to overlooked case ordering, which may account for part of the swing. Tierney's article also reported work on German car buyers and suit customers, who grew more likely to accept default options as a long run of choices went on, and that line of work is the closest to ordinary shopping.
Other settings show drift without a break to blame. Jeffrey Linder and colleagues examined 21,867 visits for acute respiratory infection across 204 clinicians in 23 primary care practices. The odds of an antibiotic prescription were about a quarter higher in the fourth hour of a clinic session than in the first. The authors used time within the session as a stand-in for decision fatigue and noted that other factors could contribute.
Financial analysts, who often issue several forecasts in a day, were the subject of work by David Hirshleifer and colleagues. Their abstract reports that accuracy fell as the number of forecasts already issued that day rose, and that later forecasts leaned more on simple rules: following the consensus, repeating the analyst's own earlier forecast and rounding.
All three records are observational. They show that decisions change across a session. They do not show that a depleted resource is the reason, and each has a rival account in scheduling, case mix or a decision to spend less effort when little is at stake. The rationing version of that last account is set out in Does Decision Fatigue Spoil Our Choices.
Some Advice Needs the Theory and Some Does Not
The popular advice is to save willpower for what matters, by wearing the same clothes, eating the same breakfast and removing small choices. That advice depends on the mechanism, the claim with the weakest support. Other advice depends only on the pattern. If decisions drift across a long session, putting weighty ones early and building in breaks costs little, and it holds whichever explanation turns out to be right.
The three field records follow experts who make many similar decisions in a row, which is a narrower setting than a day of mixed choices at home. A long appointment list or a day of approvals is the kind of setting where the pattern is worth looking for, and the studies above show how: compare early and late decisions by the same decision makers. A default that removes the choice, covered in Why the First Option Gets Picked, needs no such story. The test can be local: compare the decisions you control, early against late, before changing anything.
| Claim | Where the evidence stands | What follows for advice |
|---|---|---|
| Mechanism: choosing uses up a shared resource | Not found in the largest preregistered test | Advice that rests on it is weakest |
| Pattern: later decisions differ from early ones | Seen in records of real decisions, cause disputed | Order and breaks cost little and hold either way |
| Advice: cut choices to keep something in reserve | Partly dependent on the mechanism | Defaults that remove the choice need no such story |
Common questions
What is decision fatigue?
Decision fatigue is the idea that making many decisions in a row makes later decisions worse, lazier or more impulsive. It was popularised in 2011 and rests on ego depletion, a mechanism that large preregistered tests have not reproduced. Field studies still show decisions shifting across a session, with causes disputed.
Is decision fatigue real?
The pattern appears in several records of real decisions, including parole rulings, clinic visits and analyst forecasts. The explanation is where the evidence is weak. A 2021 test across 36 laboratories did not find the depletion effect, and the field studies cannot separate tiredness from scheduling or effort rationing.
Who coined the term decision fatigue?
Baumeister and colleagues introduced ego depletion in 1998, and the choice-specific version followed from Vohs and colleagues in 2008. John Tierney's August 2011 article in The New York Times used the phrase decision fatigue and brought it to a wide audience.
Sources
Kahneman, D. (2011). Thinking, Fast and Slow. New York: Farrar, Straus and Giroux. Seed book; vault hub Books/Thinking Fast and Slow.
Tierney, J. (2011, August 17). “Do you suffer from decision fatigue?” The New York Times.
Baumeister, R. F., Bratslavsky, E., Muraven, M., & Tice, D. M. (1998). “Ego depletion: Is the active self a limited resource?” Journal of Personality and Social Psychology, 74(5), 1252-1265. doi:10.1037/0022-3514.74.5.1252 https://doi.org/10.1037/0022-3514.74.5.1252
Vohs, K. D., Baumeister, R. F., Schmeichel, B. J., Twenge, J. M., Nelson, N. M., & Tice, D. M. (2008). “Making choices impairs subsequent self-control: A limited-resource account of decision making, self-regulation, and active initiative.” Journal of Personality and Social Psychology, 94(5), 883-898. doi:10.1037/0022-3514.94.5.883 https://doi.org/10.1037/0022-3514.94.5.883
Vohs, K. D., Schmeichel, B. J., Lohmann, S., et al. (2021). “A multisite preregistered paradigmatic test of the ego-depletion effect.” Psychological Science, 32(10), 1566-1581. doi:10.1177/0956797621989733 https://doi.org/10.1177/0956797621989733
Danziger, S., Levav, J., & Avnaim-Pesso, L. (2011). “Extraneous factors in judicial decisions.” Proceedings of the National Academy of Sciences, 108(17), 6889-6892. doi:10.1073/pnas.1018033108 https://doi.org/10.1073/pnas.1018033108
Weinshall-Margel, K., & Shapard, J. (2011). “Overlooked factors in the analysis of parole decisions.” Proceedings of the National Academy of Sciences, 108(42), E833. doi:10.1073/pnas.1110910108 https://doi.org/10.1073/pnas.1110910108
Linder, J. A., Doctor, J. N., Friedberg, M. W., Reyes Nieva, H., Birks, C., Meeker, D., & Fox, C. R. (2014). “Time of day and the decision to prescribe antibiotics.” JAMA Internal Medicine, 174(12), 2029-2031. doi:10.1001/jamainternmed.2014.5225 https://doi.org/10.1001/jamainternmed.2014.5225
Hirshleifer, D., Levi, Y., Lourie, B., & Teoh, S. H. (2019). “Decision fatigue and heuristic analyst forecasts.” Journal of Financial Economics, 133(1), 83-98. doi:10.1016/j.jfineco.2019.01.005 https://doi.org/10.1016/j.jfineco.2019.01.005