Long-term motor learning: Effects of varied and specific practice

According to the schema theory, variability during practice allows for a larger repertoire of movements to help form a generalized motor program for similar motor skills. Varied training is thought to enhance long-term retention of the motor program due to the heightened difficulty presented. In a highly cited study on this topic, Kerr and Booth (Perceptual and Motor Skills 46 (1978), 395-401) trained two groups of children for 10weeks to throw a beanbag towards either one central target (specific group) or two targets that were ±1 foot away from the central target (varied group). They found that the varied group performed significantly better than the specific group when both groups were tested at the central target. We, following the same paradigm, trained 30 adults on a similar beanbag throwing task and tested them at various target distances. Our results suggested that after 5-7weeks of training, the specific groups tended to undershoot at longer distances and overshoot at shorter distances while the varied group tended to center their throws around the target at all distances. However, the overall magnitude of error (regardless of over- or undershooting) was similar across groups. We found some support for the hypothesis that the varied group could better generalize to untrained distances, but this advantage was found mainly for the longest distance and disappeared by a posttest held two weeks after practice.