Facilitation of learning induced by both random and gradual visuomotor task variation

Motor task variation has been shown to be a key ingredient in skill transfer, retention and structural learning. However, many studies only compare training of randomly varying tasks to either blocked or null training, and it is not clear how experiencing different non-random temporal orderings of tasks might affect meta-learning processes. Here we study learning in human subjects who experience the same set of visuomotor rotations, evenly spaced between -60° and +60°, either in a random order or in an order in which the rotation angle changed gradually. We compared subsequent learning of three test blocks of +30° → -30° → +30° rotations. The groups that underwent either random or gradual training showed significant (p<0.01) facilitation of learning in the test blocks compared to a control group who had not experienced any visuomotor rotations before. We also found that movement initiation times in the random group during the test blocks were significantly (p