Decision fatigue — or why the twentieth choice of the day can be harder than the first

From the "Our Everyday Mind" series

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It's evening. You've had a day in which nothing serious happened, but in which you chose, without pause: how to answer a delicate email, whether or not to postpone a meeting, what to buy, what to leave on the shelf, how to word a sentence so it wouldn't upset anyone, whether to say yes or no to a favor. None of the choices was big. All of them, together, were.

And now someone asks you, with the greatest gentleness: "What do you want to eat?"

And you feel something like a door closing. Not that you don't know what you want. But that you have nothing left to choose with. You say "whatever you want," or you pick the first thing that comes to mind, or you get irritated for a reason you couldn't explain. A simple question has become, without your noticing, the last drop.

The name a journalist gave to a hypothesis from the lab

The phrase decision fatigue entered everyday language in 2011, through an article by the journalist John Tierney in The New York Times Magazine, titled Do You Suffer From Decision Fatigue?. Tierney was writing a book about willpower with the psychologist Roy Baumeister at the time, and the article brought before a wide audience an idea Baumeister had been studying for more than a decade.

In the lab, the idea was called ego depletion . In a 1998 study, Baumeister and his colleagues — Ellen Bratslavsky, Mark Muraven, and Dianne Tice — observed that people who had resisted the temptation of freshly baked chocolate cookies gave up sooner, immediately afterward, on a frustrating puzzle, compared to those who had had nothing to refuse. The proposed conclusion: self-control works like a muscle, which tires with every effort and needs rest to recover.

Ten years later, in 2008, Kathleen Vohs, Baumeister, and other colleagues published, in the Journal of Personality and Social Psychology, a study whose title says almost everything: Making Choices Impairs Subsequent Self-Control. Participants who had been made to make a long series of choices — between products, between versions of a university course — persisted less, afterward, on unpleasant or difficult tasks than those who had merely evaluated the same options without choosing. It wasn't contemplating the options that tired people out. It was the choosing itself.

From there, it's a short step to the formula we repeat today: every decision uses something up, and when the tank is nearly empty, the decisions that follow come out weaker.

The judges who gave more lenient verdicts after lunch

The study that made the idea famous appeared the same year as Tierney's article. In 2011, in the Proceedings of the National Academy of SciencesShai Danziger, Jonathan Levav, and Liora Avnaim-Pesso published Extraneous Factors in Judicial Decisions, an analysis of more than a thousand rulings by parole boards in Israel.

The result was spectacular: the proportion of rulings favorable to prisoners started at roughly 65% at the beginning of each session, dropped gradually toward almost zero as the break approached, then jumped abruptly back to 65% right after the meal. The authors' interpretation: as the judges grew tired, they increasingly chose the option that required the least mental effort — rejecting the request, that is, keeping things as they were.

The story was picked up everywhere. The hungry judge became the emblematic image of decision fatigue. We'll come back to him, because the story has a lesser-known sequel.

From the courtroom to the shopping cart

You don't need a parole board to recognize the pattern.

You find it in the way, at the end of a long shopping trip, you grab whatever's at the checkout without thinking — the sweets aren't there by accident. In the configurator for a car or a laptop, where, after choosing the color from 50 options and the upholstery from 20, by the tenth field you're ticking "standard" on everything, just to be done. A field study published in 2010 by Jonathan Levav and colleagues, on customers configuring made-to-order cars, showed exactly this: when the options with many alternatives came first, people fell back more and more, in the fields that followed, on the default.

You find it in less commercial things, too. In the evening when, after a day of small decisions, you can no longer choose a film and scroll for half an hour without starting anything. In the sharp answer given to someone close, not because they did anything wrong, but because they were the twentieth person that day who needed an answer from you.

For me, it shows up most visibly on days when I have many conversations that demand attention — each with its own small questions: how far do I push, when do I stay quiet, what do I say and what do I keep. In the evening, decisions I'd make in three seconds in the morning suddenly become heavy. Not heavy to solve — heavy to begin. I've learned not to make important decisions on those evenings, not because I'd think poorly, but because I notice that I no longer want to think at all. Decision fatigue doesn't feel like fatigue. It feels like indifference.

What the mind is actually trying to do

The classic explanation — Baumeister's — says the mind literally consumes a resource: that willpower and decision draw on the same limited reservoir, which every choice drains a little. For a few years, this resource was even identified with blood glucose; the idea that a glass of lemonade restores self-control circulated widely, but the biological mechanism has been seriously called into question.

An alternative explanation, proposed by researchers such as Michael Inzlicht, doesn't speak of a reservoir that empties, but of a motivation that shifts. After a series of efforts, the mind doesn't run out of energy; it becomes, rather, less willing to spend it. Attention slides from what must be done toward what would be pleasant to do, and effort starts to be felt as carrying an ever-higher cost. In this reading, decision fatigue isn't a sign that you've run out of fuel. It's a signal — perhaps a useful one — that something in you is asking for a change of pace.

The difference isn't merely academic. If it's an empty reservoir, the solution is a break and some glucose. If it's a motivation that has shifted, then why you choose matters as much as how many times you choose — and the same number of decisions can exhaust you completely one day and not at all the next.

What happened to the hungry judges — and to the willpower muscle

Here things get more complicated, and it's worth saying so openly.

A few months after the judges study, the same journal published a letter from Keren Weinshall-Margel and John Shapard, who raised a simple problem: the order of the cases wasn't random. In those boards, prisoners without a lawyer were usually heard at the end of the session, and lawyers representing several prisoners could arrange their order strategically. The weaker cases, in other words, systematically landed before the break — which could explain, at least in part, the spectacular curve. A 2016 analysis by Andreas Glöckner showed, through simulations, that simple time scheduling — cases with a chance of approval take longer and no longer fit before the break — can produce part of the effect as well. Other researchers have pointed out that an effect that large would be, statistically, nearly impossible to obtain from fatigue alone.

And the broader theory the idea was born from — ego depletion — has since gone through a hard test. In 2016, a preregistered replication across 23 laboratories worldwide, with more than 2,000 participants, found no effect different from zero. In 2021, a second replication, led by Kathleen Vohs herself, across 36 laboratories and more than 3,500 participants, found an effect so small it's hard to distinguish from nothing. Baumeister has contested the protocols used, and the debate isn't over. But the image of the tiring muscle, so intuitive, no longer stands the way it did in 2011.

What remains, then? The experience remains — which almost anyone recognizes — along with a few more modest observations, which try to explain the phenomenon without the simple model of a reservoir that empties. A 2010 study by Veronika Job, Carol Dweck, and Gregory Walton showed that the depletion effect appeared mainly in people who believed willpower was a limited resource; those who didn't believe this didn't seem to tire the same way after a difficult task. In a 2020 conceptual analysis published in the Journal of Health Psychology, Grant Pignatiello, Richard Martin, and Ronald Hickman propose that we see decision fatigue not as a trait or a deficit, but as a state that arises from sustained cognitive, emotional, and decisional load over time — a response, not a weakness.

Perhaps the truth lies somewhere between the two extremes: neither a reservoir that drains mechanically with every choice, nor the invention of a newspaper article. Something that exists, but that depends far more than we thought on what those choices mean to us.

What would change, knowing this

That the indifference at the end of a day full of choices — "I don't care, you pick" — isn't necessarily a lack of involvement. It may be the way your mind tells you it has decided enough.

That not all decisions tire you equally. The ones that ask you to give something up, to choose between nearly equal options, or to account for what others feel seem to cost more than the ones with an obvious answer — and a day with twenty easy decisions can be less tiring than one with three hard ones.

That the science behind the concept is more fragile than the headlines using it suggest, and that it's fine to keep that in mind: if something works for you — leaving important decisions for the morning, cutting down on small choices — it works, regardless of the fate of the willpower muscle in the research literature.

Perhaps the question isn't how many decisions you can make in a day before you tire. Perhaps it's which kinds of decisions tire you — and what that says about what actually matters to you.

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If you feel you want to explore more of what is happening in your emotional life, there is a space for that.