Early event-related brain potentials and hemispheric asymmetries reveal mind-wandering while reading and predict comprehension

• P1 and N1 were attenuated when individuals were mind-wandering while reading.
• Individual differences in P1–N1 predicted reading comprehension.
• Prediction by P1–N1 was independent of variance in general intelligence.

The electroencephalogram (EEG) of mind-wandering (MW) was examined in event-related potentials (ERPs) and pre-stimulus alpha (8–12 Hz), over lateral-posterior sites of left and right brain hemispheres, while individuals read text passages. After controlling for individual differences in general intelligence (g), P1-asymmetry was greater (right-minus- left) and N1 amplitudes were more negative, when individuals were not MW (i.e., they were reading attentively). Approximately 82% of variance in reading comprehension was accounted for by the predictors: g, pre-stimulus alpha, left- and right-hemisphere P1, and left-hemisphere N1 (when individuals were not MW). Together, individual differences in MW-sensitive ERPs uniquely accounted for approximately 38% of the variance in reading comprehension, over and above prediction by g and pre-stimulus alpha. The within-person effect of MW on P1-asymmetry was estimated to account for an additional 4.6% of criterion variance. Implications for EEG/ERP research into attention, language processing, hemispheric asymmetries, and individual differences are discussed.