Procrastination is ubiquitous, but its underlying processes are poorly understood. Studies of procrastination have used self-report questionnaires and therefore have limited use as the basis for process models. As typical procrastination behavior is characterized by a delay in starting the work and rushing in the end, we argue that studies should emphasize the time course of progress. We designed a reading task to quantify the time course of procrastination. Subjects were given seven days to work online on a boring and lengthy reading task. We tested whether reward delay is a predictor of procrastination. We introduce a metric for quantifying the degree of procrastination from the time course of progress. The degree of procrastination tends to be higher in the delayed reward condition than that in the instantaneous condition. We also observed great individual variation in the progress course. Further work needs to investigate what factors contribute to this variability.

Procrastination is prevalent. Empirical studies of procrastination have identified various contributing factors underlyingprocrastination. Models of procrastination, however, have only considered temporal discounting and have ignored otherfactors. Moreover, existing models of procrastination are mostly conceptual, and there is a lack of process models toexplain why people procrastinate. Here, we use reinforcement learning theory to build a process model of procrastination.The model assumes that people maximize expected utility while minimizing the total cost of the effort. Our model makesseveral predictions: 1. Strong temporal discounters will delay working early and rush to work near the deadline; 2. If atlow effort cost, cost is sensitive to increases in effort, people will delay working until the last minute; 3. If time pressure oreffort cost is high, perfectionists will not work at all. We designed a behavioral experiment to study the factors underlyingprocrastination and to test our model predictions.

Procrastination is ubiquitous, but how to reduce procrastination is rarely examined in a behavioral experiment. We hypothesized that procrastination is reduced when the reward is immediate versus delayed, and that the size of reduction could vary across different levels of pressure on task completion. To test our hypothesis, Subjects were assigned a week to work online on a lengthy reading task. We manipulated the reward timing (delayed versus immediate) and levels of task completion pressure. We quantified the level of procrastination with mean completion day of a paragraph, with a higher value indicating a higher level of procrastination. We found that among subjects who completed the task, there was no main effect of reward timing on procrastination level, whereas subjects who left the task unfinished procrastinated less when reward was immediate. There was no main effect of task completion pressure, and no interaction between reward timing and task completion pressure.

Procrastination is often characterized as minimal progress initially, with a significant increase in progress shortly before the deadlines. Yet, the cognitive mechanisms underlying this intriguing dynamic feature of procrastination—the time course of progress—remain poorly understood. We investigated this through an experiment where participants worked on a self-paced, week-long online reading task consisting of numerous work units (N = 611). We proposed two models that fit each individual's time course of progress. Both models consider the time course of progress as the output of sequential decision-making: whether to work now (and, if so, how much) or later. The first, a normative model, calculates the value of making progress using the Bellman equation; the second, a roll-out model, estimates this value by simulating future work progress. We found that the rollout model fit the data much better, suggesting some evidence against people behaving rationally and some evidence for people simulating future work progress.

Procrastination is universal but not monolithic; a second dimension, the Intention–Behavior Gap (IBG), has been suggested to be relevant. The IBG is the difference between one’s intentions and one’s behavior. So far, the IBG has not been directly measured within a behavioral experiment. We assigned subjects a week to work on a lengthy online reading task. Before the task started, subjects reported their plan by the number of reading units for each day. We found great variability in their plans, actual time course and the difference between the two (IBG). The time course of work ranged from completing earlier than planned to not finishing. We calculated correlations between the mean unit completion day, the IBG, the Causal Dimension Scale, indices of regret and satisfaction, and scales for procrastination (General, Active and Irrational). Besides the correlations expected based on definitions, we did not find any significant correlations.