Decision fatigue: why the eleventh decision is worse than the first

The strong version — that willpower is a depletable fuel — has not replicated well, and large multi-lab attempts failed to reproduce the classic ego-depletion effect. What does hold up is more modest and more useful: sustained, effortful decision-making produces a measurable shift in strategy. People move from effortful weighing to low-effort shortcuts — defaulting, deferring, accepting the status quo, going with whoever spoke last. The capacity may not be a tank, but the willingness to spend it clearly declines.

Fatigued decision-makers do not become randomly wrong; they become predictably conservative. In a well-known analysis of parole hearings, favourable rulings declined across each session and recovered after breaks — a finding that has been debated and re-analysed, and whose direction matches what everyone in the room reports. The practical read: the later the decision, the more likely it is that the default wins regardless of merit.

It does not restore cognitive capacity — no evidence claims that. What slow breathing at around six breaths a minute does is raise heart-rate variability, and higher vagally mediated variability is associated with better performance on executive-function tasks. That is an association in a model, not a demonstration that breathing makes you a better decision-maker. The practical value is simpler: it makes you stop for three minutes before a decision you were about to make on autopilot.