Insufficient task-outcome association promotes task procrastination through a decrease of hippocampal-striatal interaction

Theories on procrastination propose that associating tasks with higher valued incentive outcomes results in less task procrastination. However, it remains unknown how representation of incentive outcomes and task-outcome association are mediated by the human brain. Using event-related functional magnetic resonance imaging, we scanned human participants while they were thinking about both tasks and the incentive outcomes each task can yield in an unconstrained way. Results showed that tasks that are more likely to be procrastinated are associated with less value in incentive outcomes. Interestingly, procrastination was more likely if it was more difficult for participants to associate a task with its valued incentives when thinking about the task (i.e., the decreased task-outcome association). On the neural level, higher value of rewarding outcomes was correlated with increased putamen activations, which further negatively predicted task procrastination. On the other hand, when participants were associating tasks with the incentive outcomes, the decreasing task-outcome association corresponded to decreasing activation in putamen, and a decreasing hippocampus-putamen coupling which further mediated the effect of the insufficient task-outcome association on procrastination. In particular, the current findings show that procrastination is more likely when people are less able to associate tasks with highly valued incentives, which is accompanied by reduced hippocampal-striatal interactions during task construction.