Abstract
<p>Procrastination is costly and pervasive, and delivering rewards immediately is a widely recommended intervention in self-help advice, yet this advice lacks experimental support. A key challenge in testing it is designing a paradigm that both mimics real-world environments where procrastination arises and permits experimental manipulation. Here we introduce the Multi-day Online Reading Task (MORT), which combines these properties and enables measurement of the full time course of work. In a preregistered experiment (n = 611), participants were given seven days to complete a self-paced reading task and received payment either immediately upon task completion or one day after the deadline. Immediate reward led all participants to start earlier and led those with high trait procrastination, who need help most, to complete work units and the overall task earlier across three reward-performance relationships. The benefits were mediated by motivation and did not come at the cost of task completion or persistence. These findings provide causal evidence that immediate reward reduces procrastination.</p>