Learning volleyball serves: a preliminary study of the effects of knowledge of performance and of results.

Recently, doubts have begun to surface about the emphasis that for years has been given to the variable knowledge of results in motor learning, and a view has been expressed that information on how an action has been made (knowledge of performance) may be of more use. This study compared the two types of information in learning a volleyball serve by eight subjects, who were given the two kinds of feedback at various points in the process. Analysis seems to show that knowledge of performance tends to be more effective for learning and that there may be interference across information if knowledge of results is provided after knowledge of performance.