A control policy can be adapted to task demands during both motor execution and motor planning

Abstract

Movement planning consists of several processes related to the preparation of a movement such as decision making, target selection, application of task demands, action selection and specification of movement kinematics. These numerous processes are reflected in the reaction time, which is the time that it takes to start executing the movement. However, not all the processes that lead to motor planning increase reaction time. In this paper, we wanted to test whether tuning feedback gains to task demands contributes to reaction time. Taking into account that the tuning of feedback gains differ for narrow and wide targets, we used a timed response paradigm in order to track the amount of time needed to tune feedback gains appropriately to task demands. We discovered that it does not take any time during motor planning and even that it can occur indistinguishably during motor planning or during motor execution. That is, the tuning of feedback gains was equally good when the narrow or large target was displayed before than when it was displayed after. These results suggest that the frontier between motor planning and execution is not as clear cut as it is often depicted.