A series of experiments examined motor learning as an information processing activity occurring within a working short-term memory system and where response-produced feedback and knowledge of results (KR) are used to modify the action plan developed from previous attempts at the movement task. Use of interpolated activities in the KR delay interval allowed inferences to be made regarding the capacity and structural characteristics of these information processes. Results indicated no capacity limitations on the learning process but important structural effects were found. The results supported the idea that response-produced feedback is relatively unimportant as a feedback variable early in learning. Rather, the use of KR at a relatively high level of movement planning appears to be the important information processing activity underlying learning. Finally, the results supported the view that these information processes are related to cognitive problem solving activities.