Human movement patterns predict task-unrelated thought

The cognitive phenomenon, known as task-unrelated thought, reflects the attention shift of one's mind away from the task at hand. Evidence suggests that task-unrelated thought occurs in 30-50% of people's waking time. Previous research using the metronome response task shows that task-unrelated thought is related to variability in response time magnitude. However, those studies did not account for the time varying characteristics of an individual's tapping behavior. In the current study, three research questions were investigated: (1) What is the relationship between task-unrelated thought and movement dynamics (finger tapping dynamics)? (2) How does the statistical structure of external stimuli influence task-unrelated thought? (3) Does this structure moderate the relationship between task-unrelated thought and finger tapping dynamics? Participants performed the metronome response task under four different metronome structures: NoTone, Persistent, Periodic, and Random. Participants synchronized their finger to the metronome tone for each condition and self-reported the occurrence of task-unrelated thought. Overall, an increase of the Hurst exponent resulted in a decrease of task-unrelated thought probability. The findings have implications that behavioral variability has value in detecting task-unrelated thought. Additionally, studies using the metronome response task should account for the impact of the tone structure being used. Future research is warranted in this field to truly understand the mechanism behind task-unrelated thought and its link to human movement variability.