Stimulating minds to wander

Springing from memory and imagination, mind wandering is a mental state occupying as much as half of our waking life, involving a shift of attention away from the external environment and toward task-unrelated concerns (1). Although mind wandering may play an important role in planning and creativity (2, 3), it is also widely associated with negative mood and degraded performance on measures of vigilance, working memory, fluid intelligence, and reading comprehension (4, 5). The intrinsically subjective and spontaneous nature of mind wandering has made it difficult to investigate with direct experimental manipulations (6). Researchers have used various approaches to do so indirectly, by altering related factors such as mood, motivation, the amount of time spent on a task, or cognitive load (7, 8). However, these factors may influence various cognitive processes besides mind wandering. Moreover, these approaches do not directly implicate underlying neural mechanisms of mind wandering. In contrast, Axelrod et al. (9) demonstrate that mind wandering can be increased by direct experimental manipulation of brain activity using transcranial direct current stimulation (tDCS) to the prefrontal cortex (PFC). The article by Axelrod et al. thus marks a new era for research into mind wandering and previews some of the insights that continued methodological advances will likely make possible.