Abstract
The main approaches to the assessment and investigation of motor performance are briefly reviewed and the current explanation of the nature of human skills in terms of engineering concepts is discussed. In relation to motor skills in particular, an attempt is made to discuss the findings of experimental and other studies in terms of the underlying organization of muscle activity. It is proposed that a key feature of motor skill is the consistency of the movement pattern and the implication of this is discussed for an explanation of the development of handedness.