Random and Blocked Practice Schedule Affect Search for New Movement Coordination Patterns Differently

Learning a novel motor task involves searching within the joint space to form new movement coordination patterns that achieve the task goal. This search process is characterized by systematic changes in joint angle coordination over time, requiring variability in coordination patterns. Motor learning studies have often highlighted the benefits of practice variability on task performance and have primarily focused on search processes at the task level, neglecting the underlying joint level. This study aims to identify differences due to imposed task variability in search behavior within both the task space and the joint space. Participants were divided into two groups based on their practice schedule (blocked vs. random) and performed a lateral interception task using a novel body–machine interface paradigm with redundant mapping between movement signals and paddle position. The results showed that participants successfully learned the required movement coordination in both practice groups. However, random practice led to increased search behavior at both the task and joint levels. Furthermore, analysis of the search structure revealed that covariation in coordination patterns was higher with random practice. Introducing variability during practice did not affect task performance but significantly influenced the amount and structure of search behavior.