When we exercise, our muscles ache, fuel reserves (glucose, ATP) deplete, and the hours that follow are well described by the word ‘fatigue’. Prolonged thinking, too, comes with costs; while we might not gasp for breath during an exam, everyone is familiar with the feeling of exhaustion after a sustained bout of cognitive effort. In their review, Pessiglione et al. [1] formalize this intuition with an integrative model that combines motivational and metabolic mechanisms. Their MetaMotiF framework offers a compelling account of why the exertion of cognitive control becomes increasingly difficult over time.
