ABSTRACT
Research on motor skills has given pride of place to the hand as the effector system for manipulative and control skills and, of course, the trunk and limbs are the principal effectors in whole body skills. The central issue for research on skill is how the effector mechanisms are successfully brought to bear on objects in the environment in order to fulfil the goals of the organism. Simple positioning tasks such as placing a peg in a hole illustrate two types of control in one movement, a pre-programmed, ballistic or open-loop initial phase followed by a controlled or closed-loop second phase. The pre-programmed phase has been taken as evidence for a general mode of feedforward control by means of a motor program. Feedback theory has been applied to a wider range of problems than just the control of simple motor acts.
