Fig. 2. Different functional hierarchies for movies, rest, and tasks.

We estimated the functional hierarchy as characterized by the levels of NR. (A) Direct comparison of hierarchy in naturalistic movie, rest, and tasks shows that movie-watching (averaged over all sessions) has a significantly more flattened hierarchy (i.e., lower NR) compared to both rest and tasks (average over all seven tasks). Rest is less nonreversible than movie-watching but significantly less than task. (B) Each session of movie-watching (measured with 7-T fMRI) is significantly less nonreversible than rest. (C) Equally, all seven cognitive tasks (measured with 3-T fMRI) are significantly more hierarchically (i.e., nonreversible) than rest, suggesting the importance of hierarchy for computation.