Differences in incidental and intentional learning of sensorimotor sequences as revealed by event-related brain potentials

The present study investigated differences in sequential learning between subjects who were or were not informed of the presence of a repeating sequence (intentional or incidental group, respectively). Subjects had to learn a 16-letter-long repeating sequence that was irregularly disrupted by deviating stimuli. Reaction times indicated that both groups learned the sequential regularities. Intentional learners showed a larger learning effect. Event-related brain potentials (ERPs) recorded during performance of the task showed a reliably enhanced amplitude for the N2b- and P3b-components for deviant letters for intentional learners, but not for incidental learners. These results are discussed in the context of models proposing that different neural structures are involved in implicit and explicit serial learning.