Motor programming: does the choice of the limb which is to carry out the response imply a delay?

In many activities, the human being must quickly decide on the response to be produced following a change in the environment. In some of these situations, the limb that the individual chooses to carry out a response seems to be a significant element in performance. Thus, if the individual carries out the response with the limb closest to the target, the performance can improve because it will take less time to achieve the goal. However, it seems that in these situations, the human being does not take this decrease in movement time into consideration and that the response is carried out with the dominant hand. Why is this so? It may be because the reaction is faster when there doesn't have to be a choice as to which limb will carry out the response. The goal of this study was to check this possibility. In order to do so, the subjects performed a two choice reaction-time task. For this task, some subjects knew beforehand which hand they had to use to carry out the response while other subjects were unaware of this fact. The results of two experiments indicated that the choice of the limb which is to carry out the response requires no particular delay when the movement to be produced is externally guided.