Response Anticipation Processes in the Learning of a Sensorimotor Sequence

Abstract We investigated the contribution of motor processes to implicit and explicit serial learning by means of event-related brain potentials. An otherwise predictable sequence of S-R pairs was occasionally interrupted by stimuli that violated either the stimulus or the response sequence (perceptual or motor deviants). After performing the task, participants were asked to recall as much of the sequence as possible. On the basis of these free recall results, two groups of subjects (explicit and implicit learners) were formed. Reaction time was prolonged for motor deviants but not for perceptual deviants, which violated the predictable sequence of stimulus locations. Early activation in the lateralized readiness potential (LRP) for standard stimuli and an activation of the expected but incorrect response for deviants violating the response sequence indicate the contribution of motor processes to serial learning. ERPs did not show any learning-related changes. Furthermore, in all dependent measures no differences between explicit and implicit learners were observed. The results are at variance with previous claims that serial learning is a purely perceptual process.