The role of task difficulty in theoretical accounts of mind wandering.

Recent research has indicated that reducing the difficulty of a task by increasing the predictability of critical stimuli produces increases in intentional mind wandering, but, contrary to theoretical expectations, decreases in unintentional mind wandering. Here, we sought to determine whether reducing task difficulty by reducing working-memory load would yield similar results. Participants completed an easy (Choice Response Time; CRT) task and a relatively difficult (Working Memory; WM) task, and intermittently responded to thought probes asking about intentional and unintentional mind wandering. As in prior studies, we found higher rates of intentional mind wandering during the easy compared to the more difficult task. However, we also found more unintentional mind wandering during the difficult compared to the easy task. We discuss these results in the context of theoretical accounts of mind wandering.