Prior EEG marks focused and mind-wandering mental states across trials

Whether spontaneous or induced by a tedious task, the transition from a focused mental state to mind wandering is a complex one, possibly involving adjacent mental states and extending over minutes or even hours. This complexity cannot be captured by relying solely on subjective reports of mind wandering. To characterize the transition in a mind-wandering-inducing tone counting task, in addition we collected subjective reports of thought generation along with task performance as a measure of cognitive control and EEG measures, namely auditory probe evoked potentials (AEP) and ongoing 8-12 Hz alpha-band amplitude. We analyzed the cross-correlations between timeseries of these observations to reveal their contributions over time to the occurrence of task-focused and mind-wandering states. Thought generation and cognitive control showed overall a yoked dynamics, in which thought production increased when cognitive control decreased. Prior to mind wandering however, they became decoupled after transient increases in cognitive control-related alpha amplitude. The decoupling allows transitory mental states beyond the unidimensional focused/wandering continuum. Time lags of these effects were on the order of several minutes, with 4-10 min for that of alpha amplitude. We discuss the implications for mind wandering and related mental states, and for mind-wandering prediction applications.