Learning and reminiscence as a function of target predictability in a two-dimensional tracking task

Twenty subjects performed one of two types of a two-dimensional tracking task for two 5-min sessions, separated by a 10-min rest. In task I, both the horizontal and the vertical components of target movement were unpredictable. In task II, the horizontal component of target movement was predictable (sinusoidal), while the vertical movement was unpredictable. There was no change in level of performance throughout the 10 min of practice on task I. For task II's predictable component, there were marked within- and between-session improvements in performance; whereas for the unpredictable component there was only a between-session improvement. It is proposed that, in these tracking tasks, improvement with practice depends on the development of programmed sequences of movement which can only occur for predictable target movements. Only after a rest do these programmed sequences become automatic, releasing spare attentional capacity for improving the performance of any unpredictable components of the task.