Implicit motor sequence learning is not represented purely in response locations.

This study employed a novel variant of the serial reaction time task, focused on sequencing one element of movement-direction. During the task a repeated pattern of alternating directions (right-left-right, etc.) was embedded in the stimuli, and there was no series of response locations. Responses were made via two effector systems: single-finger responding (necessitates lateral arm movements between response keys), and four-fingered responding (4 individual fingers on 4 individual keys; requires no lateral arm movement). The sequence of directions was only learned by participants who performed lateral movements during training, indicating that learning was contingent on the particular motor effector used. Participants with low levels of sequence awareness displayed the same pattern of results.