Decreasing propensity to mind-wander with transcranial direct current stimulation.

Mind wandering or task-unrelated thought (TUT) is associated with various impairments as well as with adaptive functions, indicating the importance of regulating this process. Although Axelrod et al. (2015) have shown that anodal/cathodal transcranial direct current stimulation (tDCS) of the left/right lateral prefrontal cortex (LPFC) could increase the propensity for mind wandering, it remains unclear whether a different tDCS protocol could have the reverse effect. The present study investigated whether and how simultaneous stimulation of the left LPFC and right inferior parietal lobule (IPL) could modulate TUTs. These areas may be crucial for regulating both TUTs and its neural underpinning (default mode network). We applied tDCS to the right IPL/left LPFC prior to a perceptually demanding flanker task and compared TUT propensity during the task among tDCS groups. We found that TUT propensity was reduced by anodal/cathodal tDCS of the right IPL/left LPFC compared with cathodal/anodal tDCS, and the results for the sham group were intermediate between these two groups. This is the first study to demonstrate that tDCS can decrease, as well as increase, TUT propensity.