The one-target advantage: advanced preparation or online processing?

The one-target advantage refers to a shorter movement time for one- target aiming movements, in comparison to aiming attempts followed by a second movement. Theoretical explanations of the one-target advantage vary in the extent to which they attribute this phenomenon to prior planning or to online control mechanisms. In this research, we attempted to gain insight into the control of sequential aiming movements by manipulating the availability of online feedback during this first or second movement component. When the participants vision was occluded during the first movement (Experiment 1) or during the second movement (Experiment 2), their performance was affected, showing that vision was important for online control of the movement sequence. A one-target advantage was found when the second movement was in the same direction as the first, but not when it was reversed with respect to the home button. Both prior planning and online control processes contribute to the one-target advantage. The degree to which these processes are important for limb control depends on the specific task demands