Decision Fatigue at Work: What's True and What Isn't

Abstract

This article is about a popular idea and how well it holds up: decision fatigue at work. Three pieces of research bear on it. A study of parole decisions by experienced judges (Danziger and colleagues, 2011) found that the share of favourable rulings fell within each session and recovered after a break. A simulation study (Glöckner, 2016) showed that a rational judge managing the time left in a session can produce a similar pattern, and concluded that the original effect is likely overestimated. A replication by 23 laboratories with 2,141 participants (Hagger and colleagues, 2016) found a very small pooled effect for the wider idea that self-control is a limited resource. None of these studied finance staff. The three steps at the end are practical readings, not tested methods, and this article is not medical advice.

The invoice question at four o'clock

It is a close day. Since eight you have approved forty journals, answered sixty emails and settled a dozen small questions that other people could not.

At four, a supplier asks where to send an invoice. The answer is the same as it has been for three years, and you stare at the message for a full minute. You think: decision fatigue. Then you wonder whether that is a real thing or just a phrase.

Decision fatigue at work: what is the evidence?

The research cited here does not settle whether decisions get worse as the day goes on. It covers the best-known study that suggested it, a critique that offers a different explanation for the same pattern, and a large replication of the wider idea that willpower runs down with use. Those studies used judges' rulings, simulations and laboratory tasks, and none was limited to finance. The next three sections cover what each one found. None of them tested the three steps at the end.

What a study of parole decisions found

Danziger, Levav and Avnaim-Pesso (2011) tested a popular caricature of legal realism, the idea that justice depends on what the judge ate for breakfast. They used sequential parole decisions made by experienced judges. They recorded the judges' two daily food breaks, which divided each day into three decision sessions.

The share of favourable rulings started at about 65%, declined steadily toward nearly zero within each session, and jumped back to about 65% after a break. The authors conclude that judicial rulings can be influenced by extraneous variables that should have no bearing on legal decisions. This is summarised from the published abstract and a repository page.

Read the four o'clock question through this. This is the study that made many people believe that decisions get worse across a session. This is an inference. The next section describes a different explanation of the same pattern.

What a simulation study found about the same pattern

Glöckner (2016) shows that a statistical artefact can produce a pattern like the one in the parole study. Favourable cases take longer to decide than unfavourable ones. If a judge avoids starting a case that will not fit into the time left in a session, long favourable cases are pushed out of the session, and the cases that remain look more and more unfavourable.

A simulated judge who is perfectly rational and behaves this way produces a decline of similar shape and size, without any bias. The author adds that the drop in the original study corresponds to a very large effect, much larger than estimates for mental depletion in meta-analyses, so the effect is likely overestimated. The paper does not rule out that extraneous factors play some role. This is summarised from the journal page.

Read your own afternoon dip through this. A fall across a session can have a scheduling explanation, and not only a tiredness explanation. This is an inference. The critique concerns one dataset, and it does not show that tiredness never affects decisions.

What a replication by 23 laboratories found

Hagger and colleagues (2016) begin from the view that self-control is linked with outcomes such as health, relationships and success at work and school. The resource depletion model proposes that self-control is a limited resource that becomes depleted after exertion, so that performance on a later self-control task suffers. This is called ego depletion.

An earlier meta-analysis had found a medium-sized effect, but later ones questioned whether the effect exists and how large it is. In this registered replication report, 23 laboratories with 2,141 participants in total ran a standardised protocol. The pooled effect was very small (d = 0.04, 95% CI -0.07 to 0.15), and the interval includes zero, so the study does not support a reliable effect under these conditions. This is summarised from the published abstract and a repository page.

Read the idea that willpower is a battery through this. The picture of a fuel tank that empties with use did not hold up in this large replication. This is an inference. These were laboratory tasks, not decisions at work, and the result concerns one protocol.

Decision fatigue at work: three steps

None of these is a tested method, and none was studied in finance teams. They combine what the research points to with ordinary practice. Where a step goes beyond the research, it says so.

1. Cut the number of decisions, and do not rely on stamina. Whatever causes the afternoon dip, fewer repeated calls leave less to get wrong. Turn the repeated ones into standing rules. This is a judgement, and no study cited here tested this step. For instance: "Supplier invoices under 5,000 go to the shared inbox and are paid on the 15th. I look only at exceptions."

2. Put the decision that matters ahead of the pile. Do the one important call before you open email, because you can, and not because research says mornings are better. Neither the parole study nor its critique tells you the best time of day to decide. This is a judgement, and no study cited here tested this step. For instance: "Provision sign-off at 8:30, before I read anything."

3. When you think "I'm too tired to decide", write down the one thing you do not know. Tiredness can hide an unanswered question. Glöckner (2016) shows that a pattern that looks like fatigue can have another explanation, so check for one before you blame yourself. This is a judgement, and no study cited here tested this step. For instance: "Decision: sign off the provision. Missing: the auditor's view on the valuation."

If the load comes from deadlines, How to Make Decisions Under Pressure: What Stress Changes goes into that. For the first seconds of a strong reaction, there is The 90-Second Rule at Work: What's True and What Isn't. If the close is what wears you down, see Month-End Close Stress: Why It Comes Home With You. When the decisions keep coming back to you, How to Delegate as a Finance Manager: Why Work Comes Back is about that. And Finance Director Stress: Where the Pressure Comes From looks at the wider load.

Questions People Ask

Is decision fatigue real?

Feeling worn down after many demands is an everyday experience. The evidence for a specific mechanism in which decisions get worse with use is contested. The best-known study has a critique that offers another explanation, and a large replication of the wider depletion idea found a very small effect.

Does willpower run out?

In the registered replication cited here, the pooled effect of ego depletion was very small (d = 0.04), and its interval included zero. That is one protocol in one set of laboratories, and it does not settle the question.

Should I make big decisions in the morning?

The studies cited here did not test time of day. Putting an important decision first is a practical choice, and not a research finding.

Can coaching help me decide?

Coaching is educational support for work patterns. It can help you see which decisions you keep making by default, and plan rules for them. It is not treatment. No study cited here tested coaching.

When it is more than a long day

A long day is one thing. It is more when you cannot make even simple decisions for weeks, when you feel numb, persistently low or anxious, when you cannot sleep, or when you notice physical symptoms. In those cases talk to your doctor, your occupational health service or a qualified mental health professional. This article is not medical advice. Coaching is educational support for work patterns. It is not treatment and not a substitute for it.

Sources

• 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 (Summarised from the published abstract and a repository page.)

• Glöckner, A. (2016). The irrational hungry judge effect revisited: Simulations reveal that the magnitude of the effect is overestimated. Judgment and Decision Making, 11(6), 601–610. Open access: journal page (Summarised from the journal page.)

• Hagger, M. S., Chatzisarantis, N. L. D., Alberts, H., et al. (2016). A multilab preregistered replication of the ego-depletion effect. Perspectives on Psychological Science, 11(4), 546–573. DOI: 10.1177/1745691616652873 (Summarised from the published abstract and a repository page.)