Optimal length for summary knowledge of results: the influence of task-related experience and complexity.

Because manipulations of knowledge of results (KR) are critical to motor learning, researchers have attempted to establish an optimal length for summary KR. Experiment 1 of the present study investigated the option that optimal summary length may be dependent on a subject's task-related experience. Participants in a summary 1, 5, or 15 condition practiced a simple striking task for one session on three consecutive days with each day followed by a 24-hour no KR retention test. The retention test results indicated that optimal summary length is dependent on task-related experience. Experiment 2 investigated the nature of the relationship between task-related experience and complexity and optimal summary length (summary 1, 5, or 15). Again, striking tasks (simple and complex) were used. There was one practice session with either a simple or complex striking task for either novice or experienced performers, followed by a 24-hour no KR retention test. Data from the two experiments suggest that task complexity and performer experience interact in determining optimal summary length.