DIMINISHING THE EFFECTS OF REDUCED FREQUENCY OF KNOWLEDGE OF RESULTS ON GENERALIZED MOTOR PROGRAM LEARNING

Several recent studies have shown that, compared with presenting knowl edge of results (KR) on every practice trial, withholding KR on some p ractice trials enhances the learning of generalized motor programs (GM Ps; Wulf, Lee, & Schmidt, 1994; Wulf & Schmidt, 1989; Wulf, Schmidt, & Deubel, 1993). In this study, whether this effect may result from an uncertainty on the part of participants about when KR is to be present ed was determined by examining the GMP learning of two 67% relative-fr equency KR groups-one that received advance information regarding the delivery of each KR (67% AKR) during practice trials and another that received no advance information (67% KR)-as well as that of a 100% KR group. The task required participants to produce 3 movement patterns t hat shared the same relative and absolute timing and relative amplitud e but differed in terms of absolute amplitude. KR was provided by disp laying the root-mean-square error (RMSE) score and by graphically supe rimposing the participant-produced pattern on that of the goal movemen t. The results revealed no group differences in measures of GMP develo pment or parameterization effectiveness during practice and no-KR rete ntion. However, during no-KR transfer with a novel absolute amplitude, the 67% KR group demonstrated a more accurate and stable GMP than the 67% AKR and 100% KR groups. Possible explanations for why advance kno wledge about KR delivery diminishes GMP development are discussed.