Appropriate summary KR for learning timing tasks under conditions of high and low contextual interference

Recall and retrieval processes of timing tasks were investigated in a multitask learning experiment using blocked (BL) and random (RA) practice schedules (Battig 1979). The extent to which summary knowledge of results (KR) interacts with order of presentation of practice tasks was the primary topic under investigation. It has been suggested that summary KR may enhance processing of task-relevant information (Schmidt 1991). The processing benefits of summary KR however may be dependent on the presentation order of practice tasks. Seventy-two females responded to the apparent motion of illuminated lights set at three speeds of 224, 313, and 492 cm/s during 90 acquisition, 30 no-KR retention and 20 transfer trials. Subjects' tasks was to push a ball hinged to a lever to coincide with the arrival of a light at a predetermined intercept point. Retrospective verbal reports were obtained immediately following transfer to ascertain the nature of subjects' processing activities. Error data were analyzed on four dependent variables. The most important finding was that longer summary KR lengths for RA subjects (KR10) were beneficial in acquisition and transfer. In contrast, BL subjects were more consistent in transfer if they received KR after each practice trial. A similar trend (p = 0.15) in retention was found in that BL subjects were more consistent as compared to RA, when they learned the tasks with 100% KR. Given the differential results of summary KR for BL and RA, the importance of considering the order of task presentation when investigating summary KR was supported.