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Concept: Theories about how we control coordinated movement differ in terms of the roles of central and environmental features of a control system.
After completing this chapter, you will be able to
Discuss the relevance of motor control theory for the practitioner
Define the term coordination as it relates to the performance of motor skills
Describe the degrees of freedom problem as it relates to the study of human motor control
Compare and contrast an open-loop control system and a closed-loop control system
Describe a primary difference between a motor program–based theory of motor control and a dynamical systems theory of motor control
Define a generalized motor program and describe an invariant feature and a parameter proposed to characterize this program
Define the following terms associated with a dynamical systems theory of motor control: order and control parameters, self-organization, coordinative structures, and perception-action coupling
Discuss how a motor program–based theory and a dynamical systems theory each explain the basis for the relative time characteristics of human walking and running
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To successfully perform the wide variety of motor skills we use in everyday life, we must coordinate various muscles and joints to function together. These muscle and joint combinations differ for many skills. Some skills, such as hitting a serve in tennis or getting out of a chair and into a wheelchair, require us to coordinate muscles and joints of the trunk and limbs. Other skills involve coordination of the arms, hands, and fingers; examples are reaching to pick up a pencil, playing the guitar, and typing on a keyboard. Other skills require us to coordinate our two arms or legs in such a way that each one does something different at the same time, such as when we hold a jar with one hand and screw open the top with the other or kick a ball with one leg while the other is firmly on the ground. For still other skills, where only one arm and hand are involved, we must coordinate only a few muscles and joints. We do this when we manipulate a computer joy stick or a car's gearshift.
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Motor skill performance has other important general characteristics in addition to body and limb coordination. For example, we perform some skills with relatively slow movements; think of how we position a bow before releasing an arrow or pick up a cup to take a drink from it. Other skills, such as throwing a ball or jumping from a bench to the floor, require fast, ballistic movements. Some motor skills, such as writing a numeral or buttoning a shirt, have few component parts; other skills, such as performing a dance routine or playing the piano, have many parts and therefore are very complex.
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Also, we can produce remarkably accurate and consistent movement patterns from one performance attempt to another. We are capable of performing well-learned ...