Handbook of Psychology, Volume 4: Experimental Psychology

CHAPTER 12

Motor Control

HERBERT HEUER

317

THE PROBLEM OF MOTOR CONTROL 317
An Outline of the Problem 317
An Outline of Possible Solutions 319
Indeterminateness of the Solutions 320
MOTOR PREPARATION 322
The Anticipatory Nature of Motor Preparation 323
Motor-Control Structures 324
The Advance Specification of Movement
Characteristics 326
THE USE OF SENSORY INFORMATION 327
Target Information 329
Feedback Information 333

Sensory Information for Motor Control and

Perception 334

MOTOR COORDINATION 335

Task Constraints and Structural Constraints 335

Basic Structural Constraints on Coordination 337

Levels of Coupling 340

FLEXIBILITY OF MOTOR CONTROL 342

Adapting and Adjusting to New Visuo-Motor

Transformations 342

Adjusting and Adapting to External Forces 344

MOVING ON 346

REFERENCES 346

Motor control is a cross-disciplinary field of research in
which the boundaries between established academic disci-
plines like psychology, physiology, neurology, engineering,
and physical education are blurred. Within psychology,
motor behavior tended to be a rather marginal topic for vari-
ous reasons. When psychology is conceived as a science of
the mind, movement is more or less beyond its scope. Less
obviously, even when psychology is conceived as a science
of behavior, issues of motor control do not become focal; for
example, behaviorism was more concerned with “what is
done” questions than with “how is it done” questions. Finally,
although the first well-known psychology paper on motor
control appeared at the end of the nineteenth century
(Woodworth, 1899), and although James (1890, 1950) de-
voted a chapter to “The Production of Movement,” touching
on the topic in several other chapters, the founding fathers of
psychology did not stamp motor control as an essential ingre-
dient of the emerging academic discipline.
The field of motor control gains in importance as soon as
one envisages that the human mind and brain may have
evolved primarily to support action, not to contemplate the
world. Then the question of how goals can be reached be-
comes critically important. This question alludes to problems
of control, and motor control deals with particular goals that
can be reached by moving one’s limbs.

In this chapter I first introduce the core problem of motor

control and discuss different ways that it can be solved.

Basically, there are two such ways: open-loop and closed-

loop control. Open-loop processes are initiated before a

movement is actually executed, so they are described under

the heading of motor preparation. The next section then deals

with closed-loop processes, the exploitation of sensory feed-

back from an ongoing movement in the service of motor con-

trol, but also with other uses of sensory information. After the

discussion of these rather fundamental issues, the perspective

is enlarged somewhat. Many motor skills require coordinated

movements of different limbs, which opens the topic of

motor coordination. Finally, I shall address the flexibility

of motor control which enables us to operate various tools

and machines and to handle objects of various masses.

THE PROBLEM OF MOTOR CONTROL

An Outline of the Problem

Movements result from an interplay of passive and active

forces. Passive forces are due to our own movements as well as

to environmental factors like gravity. For example, in the

swing phase of the walking cycle the thigh is rotated forward;