Abstract
Moving objects can be intercepted at various places at different times. To successfully intercept such objects one must select appropriate combinations of time and place. If, while moving towards the object, one notices that one is going to arrive slightly too early, or equivalently that one is aiming slightly too far ahead of the object, one could slow down, aim less far ahead of the object, or both. Similarly, if one notices that one is going to arrive slightly too late, one could speed up or aim further ahead. Do people adjust the place, the time or both when they detect that they are going to miss a moving target? Since there is normally no way of telling when people notice that they need to adjust their movements, we introduced errors artificially. The task was to tap virtual targets that were moving to the right across a screen with ones index finger. On some trials, the target jumped to the left or right, or closer or further from the fingers starting point, as soon as the finger started moving. Participants adjusted the position of the tap, leaving the timing unaffected. When participants were explicitly instructed to intercept the target at a specified position on the screen, they adjusted their timing as requested, tapping later for leftward target jumps and earlier for rightward target jumps. Comparing the velocity profiles revealed that participants adjusted the position that they were aiming for considerably faster than they did the timing of the tap, even when both involved speeding up or slowing down their fingers movement. This difference in latency could underlie the preference to adjust where rather than when to hit the target when no further instruction is given.
Meeting abstract presented at VSS 2014