Abstract
It is well established that people can quickly adjust goal-directed movements to small changes in the target object’s or obstacles’ positions. When the target object changes orientation people can quickly adjust their decision about how they can best grasp it. Here we examine whether they also quickly redirect their movement to a completely different object if it is advantageous to do so, and if so, whether their decisions are consistent with the true advantages (i.e. do they make optimal choices). Subjects stood in front of a large screen. There was always at least one target on the screen. Their task was to tap on as many targets as possible within 2 minutes. After every tap, a new target appeared. Sometimes, a second target that was larger and nearer, and therefore easier to hit, appeared some time after the original target had appeared. We determined the time it took each subject to hit each kind of target, as well as whether they switched to the target that was easier to hit when there were two targets. We did so for various delays before the second target appeared. We found that subjects generally switched to the easier target whenever they could hit more targets by doing so. They considered the position of their hand at the moment the easy target appeared, as well as the overall advantage of the target being nearer and larger. We found no evidence of any additional cost of determining whether it was advantageous to switch to a different target. Thus, for this kind of simple movements, visual information is used very efficiently to direct our choices as well as to guide the movements themselves.
Meeting abstract presented at VSS 2015