Experience sampling during fMRI reveals default network and executive system contributions to mind wandering

TLDR

Although mind wandering occupies a large proportion of our waking life, its neural basis and relation to ongoing behavior remain controversial. The study aimed to measure mind wandering online during a concurrent task using fMRI and experience sampling. The authors used fMRI with experience sampling probes during a concurrent task to capture neural activity associated with mind wandering. The study found that default network regions activate during mind wandering, executive network regions are also recruited, and both networks show strongest activation when participants are unaware of their mind wandering, indicating that default and executive systems cooperate during off‑task thought and highlighting the benefit of combining subjective reports with online brain measures.

Abstract

Although mind wandering occupies a large proportion of our waking life, its neural basis and relation to ongoing behavior remain controversial. We report an fMRI study that used experience sampling to provide an online measure of mind wandering during a concurrent task. Analyses focused on the interval of time immediately preceding experience sampling probes demonstrate activation of default network regions during mind wandering, a finding consistent with theoretical accounts of default network functions. Activation in medial prefrontal default network regions was observed both in association with subjective self-reports of mind wandering and an independent behavioral measure (performance errors on the concurrent task). In addition to default network activation, mind wandering was associated with executive network recruitment, a finding predicted by behavioral theories of off-task thought and its relation to executive resources. Finally, neural recruitment in both default and executive network regions was strongest when subjects were unaware of their own mind wandering, suggesting that mind wandering is most pronounced when it lacks meta-awareness. The observed parallel recruitment of executive and default network regions—two brain systems that so far have been assumed to work in opposition—suggests that mind wandering may evoke a unique mental state that may allow otherwise opposing networks to work in cooperation. The ability of this study to reveal a number of crucial aspects of the neural recruitment associated with mind wandering underscores the value of combining subjective self-reports with online measures of brain function for advancing our understanding of the neurophenomenology of subjective experience.