Because our correlate appears after the response, our finding suggests an active role for the DMN in introspective task-relevant processing, such as an active observation of the behavioral response. Such retrospection is not necessarily overtly conscious so it is challenging to investigate experimentally (Schooler, 2011). We do not believe this post-response DMN correlate is reflecting an anticipatory state while subjects await the next stimulus since ERPs (derived from EEG data that were not highpass-filtered) revealed no effect of contingent negative variation (CNV), a slow ERP component with magnitude dependent upon level of expectation of the following stimulus (Palva and Palva, 2012; Scheibe et al., 2010) (data not shown). Previously reported BOLD correlates of CNV did not include the canonical DMN (Scheibe et al., 2010); combined with our result, this loosely suggests that suppression of DMN is not related to increased anticipation. Further evidence for an introspective state late in the trial is an activation in the paracingulate, which has associations with self awareness and theory of mind, and particularly introspection-related activity during visual tasks (Goldberg et al., 2006).
