Human Motor Behavior

An Introduction

J.A. Scott Kelso, J.A. Scott Kelso, J.A. Scott Kelso

• Publisher: Psychology Press
• Year: 2014
• ISBN:
  9781317769606
• Edition: 1
• Topic: Psychology
• Subtopic: History & Theory in Psychology
• Index: Psychology

Why should anyone be interested in studying motor skills? This book is based on the contrary belief that the determinants of motor skill and the conjoint problems of how movements are coordinated and controlled are fundamentally important to anyone concerned with understanding human behavior. This includes psychologists, but applies even more especially to other disciplines-such as physical education and kinesiology-for which the subject of movement is particularly germane. In fact, this book is written primarily for undergraduates in kinesiology and physical education as well as psychology, and it may also be of interest to students in areas such as physical therapy, engineering and computer science.

I	Perspectives and Issues in Motor Behavior

Editor’s Remarks (Chapters 1 and 2)

In Chapter 1 I develop the basic perspective that understanding movement means not only recognizing the product of skilled behavior—whether a particular goal was achieved accurately and efficiently—but also questioning how it is that such skilled movements are controlled and coordinated. The tools and concepts for the student of motor behavior emerge at several different levels. At the observational/experimental level we want to understand the key relationships between environment and performer that influence the development of skill. At the biomechanical/kinesiological level we seek to understand the physical basis for movement: how dynamic factors (the forces or torques generated by muscles and their viscoelastic properties) specify the patterning of limb segments in time. At the neurophysiological level we seek insights into the neural structures and their functional interactions that allow motor behavior to emerge. I argue in Chapter 1, that this interdisciplinary enterprise is necessary to fully understand movement processes, and, further, that movement processes—rather than being given secondary or negligible status—are an intrinsic aspect of understanding intelligent behavior.

In Chapter 2 I attempt to provide an inventory—a flavor as it were—of concepts that are expanded upon in later writings. But the chapter is not meant to be a haphazard presentation of isolated topics. It starts with a consideration of the sometimes synonymously used terms coordination, control, and skill in relation to the fundamental problem for any biological system; namely, how to regulate its internal degrees of freedom. For our purposes, the degrees of freedom can be considered to be the muscles of the body—792 of them at last count: How are they organized to produce skilled activities, and how does this organization come about? One answer, that receives much further elaboration in later chapters by Michael Turvey and colleagues, is that muscles are organized into functional combinations called coordinative structures that behave in a relatively autonomous way. Thus, the brain doesn’t have to regulate every degree of freedom on an individual basis; that would create a tremendous computational burden. Rather, these lower-level muscle collectives can be “tuned” by higher centers to meet environmental contingencies. If this perspective has any validity, the motor system is not simply the slave of the senses: Perception and action are likely to be closely interwoven—not related to each other willy-nilly. Consider a skill that many of us take for granted—speaking. It is often fun (and some entertainers make a living out of it) to mimic other speakers, but imagine what this involves. Somehow, what we hear must specify how the speech muscles are to be organized in space and time if we are to mimic effectively. Information about the actions of others and about our own activities in relation to environmental demands must be crucial to the process of organizing skilled movements. With this premise in mind I go on to consider some of the basic properties of two major types of information—proprioceptive and visual—thought to be important in regulating movement. Guardedly, I refer to these sources of information as playing primarily a feedback role. But they can play a feedforward role as well. Thus, on the one hand, the performer has information about the results of activity as a potential aid to skill learning. On the other hand, skilled individuals seem able to use information effectively prior to executing a particular act. This “feedforward” information may be extrinsically defined—allowing the performer to “tune” or parameterize the system in accordance with changing environmental events. It may also take the form of patterns of neural activity within the nervous system itself, which can guide movement sometimes in the absence of peripheral information. As the reader sees, all these themes—in one guise or another—as well as many others receive further development in the chapters that follow.

1	The Process Approach to Understanding Human Motor Behavior: An Introduction

J. A. Scott Kelso

Haskins Laboratories and The University of Connecticut

Orientation

What is your conceptualization of skilled behavior? What does the word “skill” mean to you? Think about what processes underlie the exquisite coordination and timing of the ballerina, the perfectly executed pass from quarterback to wide receiver, the speed and gracefulness of a Pelé, the anticipation of a Mohammed Ali, the precision of a pianist. We all can recognize the outcome or the product of highly skilled performance, but how does this outcome materialize? What processes underlie the acquisition of skill and the control of movement? This is the overriding question that we are going to examine in some depth in the following chapters, and one that not only myself but my fellow contributors place at the forefront.

Throughout this discourse we make an implicit assumption. Namely, that striving to understand the underlying processes in acquiring skill will enable you—as students and teachers—to analyze situations in which you are confronted with a problem related to movement behavior. It may be a child who has difficulty in learning simple skills, a patient who is learning to use a prosthetic device such as an artificial limb, a skilled performer in an athletic team who, for some reason, is not performing as well as he/she might. Whatever the case, we are assuming some intrinsic benefits to you arising from a fuller understanding of what goes on when people learn skills.

Let me say at the outset that there are not many, if any, answers as to how best to acquire or teach skills. This book does not present you with an array of facts that you can immediately use in practical situations. What we are trying to communicate here is the need for you, as students of movement, to develop your own approach to the problem. A key to this is your ability to adopt a critical thinking stance on some of the issues. Think about the implications of what the information presented means to you. Try to detect flaws in the logic and suggest alternative viewpoints.

Hopefully, an important stimulus to the development of a critical approach to understanding human movement behavior comes from the perspectives provided by the different theorists contributing to this book. You will find that there are crucial points of departure on how each views the nature of skilled performance. This is all to the good because it forces you to make decisions for yourself. Throughout the following chapters you will hear people tell you a different story about the same topic—acquiring skill—usually in a plausible and logical manner. It is up to you to take your own position on the issues. It matters not at this point whether your position is right or wrong (because there are seldom any right or wrong answers!), only that the stance you take can be logically justified. Enough sermonizing. In this book we have tried to adopt a “spiralistic” approach to knowledge about human motor behavior. We begin with a discussion about component processes in movement and build progressively upon that basis to the learning and control of movements. Ultimately, we discuss how this information may be optimally applied to various skill-learning situations.

My goal in the present chapter is to give you a little background to the area of motor skills, so that the information that follows can be “slotted” into a historical perspective. I wish to recount, somewhat briefly, where the area of motor behavior has been, the changes in approach that have come about, and my own thoughts on why. I also want to give you a feel for my approach to the problems of skill acquisition, which is basically one spanning several disciplines. A full understanding of human movement, in my opinion, can only come about if we integrate behavioral work (which tends to focus on the outcome of performance) with kinesiology (which provides us with information about the kinematics of human movement) and neurophysiology (which tells us the nature of underlying neural mechanisms involved in controlling movement). I return to this point shortly with some specific examples. Firstly, let us review the past for a moment.

Brief Historical Perspective

The study of motor behavior has had a continuing, if somewhat phasic, relationship with academic disciplines such as psychology and physiology. Perhaps the relationship has not been as close as it might have been. Certainly, there have been periods during which tight bonds were established. For example, when governments were interested in optimal methods for training military personnel during World War II, a considerable number of experimental psychologists were involved in funded research. Similarly, when psychological theory (Hull, 1943) was readily testable with motor activity, psychology and motor-performance studies went hand in hand. In general however, motor tasks, such as the pursuit rotor¹, were employed as a means to an end where the “end” was exploration of psychological concepts, such as Hull’s (1943) reactive inhibition and conditioned inhibition. The explanation of these concepts is not of immediate concern but let me discuss them briefly to illustrate the type of approach taken here; and the resulting outcomes. A short discourse on Hullian theory—if nothing else— affords me the opportunity to make an important distinction between learning and performance. Hull assumed that, whenever an organism makes a response to a particular stimulus, some degree of inhibition toward that response is produced. This is called “reactive inhibition” (I_R), which was often assumed to be some type of fatigue. The notion was, therefore, that I_R would dissipate just as long as there was sufficient rest between trials. In contrast, having no rest (massed trials) should lead to a buildup of I_R (i.e., a declining response strength). This prediction is shown in Fig. 1.1, where you can see that massed trials lead to deficits in performance.

Fig. 1.1. Hypothetical performance curves illustrating the effects of massed and distributed practice (see text for further explanation).

“Conditioned Inhibition,” (_SI_R) however, is a learned behavior. Because I_R produces a negative response state (poorer performance), the organism is motivated to avoid (reactive inhibition) and through the learned habit of _SI_R is motivated not to respond. In sum, a continued buildup of I_R should lead to a permanent effect on performance. Numerous studies showed the presence of a temporary work factor (see Day 1 of figure), but there was negligible support for any permanent work inhibitor. The hypothetical data shown in Fig. 1.1 summarize the results of much of the research on this topic. Massed practice is fatigue inducing and produces inferior performance. It has, however, no permanent effect on learning.

Although this finding is of interest to teachers and coaches, it clearly tells us little about the actual movements involved. In fact, the point that I would like to emphasize is that the study of motor performance per se was not actively pursued by psychologists. Smith (1969) summed up this state of affairs quite nicely: “experimental results on and stimulus-response theoretical ideas about the pursuit rotor seem to have relevance for nothing but the pursuit rotor and even fail to give any really critical suggestions about how people operate and learn this instrument [p. 240].” The key word for us in the foregoing statement is “how, “because what we as students of motor behavior are really concerned about are the key processes underlying the acquisition of skill and the control of movement. In the past, however, much of the research carried out using motor tasks was in the behaviorist tradition. Certainly, the work on Hull’s theory that extended into the late 1950s was based on stimulus-response accounts of behavior. There was a strong concern for the conditions of reinforcement that established “habit strength” between stimulus and response exemplified by reliable performance of an act. Behaviorists, however, were not particularly concerned with the manner in which the act was attained. Implicit in the stimulus-response account was that movements were learned as a result of conditioned stimulus-response elements. Given a cue to start the movement sequence, a response would be generated that in turn would produce the stimulation to elicit a further response. Each response element is conditioned to the stimuli of the prior part of the response, and, when the elements are associatively bonded or somehow tied together, learning is complete and the motor sequence is executed smoothly. To obtain a flavor for the stimulus-response chaining model, consider the model shown in Fig. 1.2. Even the novitiate in the area realizes that this is an unsatisfactory account of human motor learning. Movements are seldom, if ever, executed the same way each time, and the stimulus-response chaining model offers little in terms of understanding the learning and regulation of motor sequences. Yet, it is surprising how long this simple model has been implicitly accepted by a large body of psychology.

Fig. 1.2. The reflex (stimulus-response) chaining model of movement behavior.

Nevertheless, different conceptualizations of motor behavior were available though largely ignored by psychology as a whole. These ideas evolved just prior to World War II and arose out of engineering circles under the name of cybernetics. The basic metaphor of a cybernetic or servotheory approach was that man behaved like a servomechanism or slave system. The common feature of the latter is that they possess a controlling device that can continuously monitor the state of the system for discrepancies between a desired and present state. Otto Mayr (1970) traces the history of such devices ranging from water clocks that used feedback control in the 3rd century B.C. to James Watt’s introduction of a governor for control of the steam engine in 1769.

In terms of the analogy to human motor behavior, the essence of the idea is expressed in a quotation from Norbert Weiner’s Cybernetics (1948):

Now suppose that I pick up a lead-pencil. To do this I have to move certain muscles. However, for all of us but a few expert anatomists, we do not know what these muscles are; and even among the anatomists there are few, if any, who can perform the act by a conscious willing in succession of each muscle concerned. On the contrary, what we will is to pick the pencil up. Once we have determined on this, our motion proceeds in such a way that we may roughly say that the amount by which the pencil i...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Preface
• Part I: Perspectives and Issues in Motor Behavior
• Part II: Information Processing, Motor Learning, and Memory
• Part III: From Component Analysis to Motor Programs
• Part IV: Generalized Motor Programs and Schemas for Movement
• Part V: Degrees of Freedom, Coordinative Structures, and Tuning
• Epilogue: Two Strategies for Investigating Action
• Glossary
• Author Index
• Subject Index