Procedural Skill Initiation, Chunks & Execution; Contributions of Offline Consolidation

It has been suggested that improvement in the performance of many motor sequence tasks such as playing musical instruments, operating complex machinery or tools, and/or performing a variety of athletic activities results from the learner?s ability to parse the movement into fundamental action primitives called motor chunks. Moreover, it has been suggested that the organization of motor chunks within a sequential behavior can be influenced by consolidation occurring outside the boundary of practice during which reorganization can occur leading to faster sequence production. The present study involved modest practice of a discrete sequence production task (DSPT) followed by subsequent assessment of performance of this task either immediately after the completion of practice or after a 24-hr delay. Of critical interest was the change in performance from the end of training to the test phase in three features of the sequence implementation namely sequence initiation, motor chunk transition, and element execution components. It was anticipated that motor chunk transition would be susceptible to significantly greater offline enhancement in the 24-hr delayed test case. Based on the extant literature it was also expected that sequence initiation and/or execution processes may also be sensitive to offline consolidation. No evidence emerged that supported the proposal that motor chunk transitions revealed additional gains following a longer interval between training and test. It is possible this effect was underestimated because of some imprecision in the manner in which motor chunk transitions were identified. There was clear evidence for offline gains for both sequence initiation and element execution processes. These data are difficult to interpret within the framework of a number of contemporary accounts of sequence production such as the dual-processor model in which sequence production is governed by a cognitive and motor processor.