Guiding Movements by Constantly Reconsidering One's Actions: A Kinematic Approach

People have to deal with a lot of uncertainty in their daily actions. This uncertainty arises from the limited resolution of their sensory processing and motor control, as well as from unpredictable changes in the environment. How do people ensure that their actions are successful when faced with all this uncertainty? We argue that they do so by constantly reconsidering their plan in accordance with their instantaneous evaluation of the circumstances. Doing so allows them to quickly respond to any changes in the environment. The response can be a small adjustment to an ongoing movement, but also diverting the movement if it suddenly becomes evident that moving toward a completely different target is more suitable for some reason. We present a simple kinematic model based on the idea that it is always beneficial to move smoothly to illustrate how continuously reconsidering movement plans can explain many findings in the literature.