Movement and Mental Imagery
Margaret Floy Washburn
FROM the point of view of scientific investigation no two subjects could present a stronger contrast than the two named in the title of this book. Movement is the ultimate fact of physical science. The measurement of the direction and velocity of movements is the most satisfactory achievement of science, and the scientist is contented with his explanation of any natural phenomenon when he has reduced it to movements and expressed their relations in a mathematical formula. On the other hand, nothing could be less attractive to the scientific investigator with such an aim than the domain of mental imagery, the world of imaginary objects. Mental images are not only removed from general observation and open to direct study only by the individual who experiences them, but even he has no satisfactory way of measuring them and reducing them to mathematics.
The movements of a living being are of all forms of movements the most complicated and difficult to study. Science is still a long way from showing that even the movements of an amoeba, the simplest of animals, arc merely combinations of the invisible movements which constitute physico-chemical processes. But at least the movements which an animal makes belong to the world of external observation; they have direction and velocity; they are movements, although very complex ones, and an investigator like Professor Loeb can entertain the confident hope that science will some day be able to show their relations to the movements of lifeless things.
It is not surprising, therefore, that since psychology undertook to call itself a science, there has existed a strong desire to connect the facts of the mind with the facts of bodily movement. There are even psychologists, who, impatient at the difficulties of showing the relation between mental phenomena
( xii) and the `behavior' or movements of the organism, have decided to abandon the attempt, to make no effort at an investigation of the inner world of sensations, images, and thoughts, and to confine all their energies to the study of how persons and animals act, how they move. For making such a decision no one can be blamed. A man has but one life, and if he prefers to invest his mental capital in an enterprise that promises quicker returns than are offered by the scientific study of the inner life, the life of the mind, he is within his rights. But he is ignoring a challenge, nevertheless: shall we say that here, in the world of conscious experiences, as distinct from the world of external movements, is a whole field of phenomena which man must leave unworked because he can borrow no tools from other fields? Perhaps it is the irritating consciousness of this challenge that has led the most extreme 'behaviorist,' Professor Watson, actually to deny that there exists any mental imagery. If we are all deluded in the belief that we possess mental images, then evidently the behaviorist who refuses to study them is wise; although even under such circumstances, one might think, a scientific investigator would feel some curiosity regarding the cause of so wide-spread a delusion. Watson (147) seems to argue that because the facts regarding mental imagery are very complicated, therefore there is no such thing as a mental image, whereas the opposite inference would be quite as natural. Because Fernald (35) and Angell (5) have shown that the differences between individual minds as regards the occurrence of mental imagery are less simple than had been supposed, "the way," he says, "is paved for the dismissal of the image from psychology." But we have just as good reason for denying the existence of all conscious processes whatever as we have for denying the existence of mental images. An outsider, studying merely my bodily movements, would be quite as unable to explain why a certain vapor should affect me with the peculiar experience of the smell of kerosene, or why certain ether vibrations should make me see red, when red does not look at all like a vibration, as he would
( xiii) be to detect the existence of purely `imaginary' smells and colors in my consciousness.
If, then, one persists in being curious about the "inner aspect" of behavior and in believing that a man's thoughts are as legitimate objects for scientific study as his movements; if on the other hand, one realizes that it is through his movements that man takes his place in the rest of the order of nature, then the proper outcome of this twofold interest is an attempt to show that the whole of the inner life is correlated with and dependent upon bodily movement. This attempt is everywhere visible in the psychological theories of the past twenty years. The excuse which the present essay would offer for its own existence is that while the facts of attention, perception, and emotion have had their relation to bodily movement fully discussed, there still remain many phenomena connected with the complexer life of the mind, the revival of past experiences and the construction of new thoughts and ideas, whose connection with motor processes has not been satisfactorily traced. Thus McDougall (73) can challenge the believers in a parallelism between mental and physical processes to show that certain forms of memory can possibly be due to associations between movements. Even the relation of consciousness itself to movement is not yet clearly conceived.
Nothing could be less dogmatic than the spirit in which this sketch of a motor theory of menial processes is put forward. There are grave dangers attending the attempt to form a complex and self-consistent theory where an appeal to fact is not possible at every step; and one of the chief dangers is that of taking self-consistency as equivalent to truth, of thinking that a subordinate hypothesis, for instance, must be true because it fits nicely with the rest of the theory, even though the whole structure be hung up in the air. And yet in psychology especially, it seems to me, one may be permitted to push theory ahead of fact. For clearly the phenomena of the mind are
( xiv) enormously complicated. When a psychologist records the results of an experimental research, he usually analyzes them only from the point of view that he had in making the research: it is so difficult to analyze them at all that he has no time to do more. Thus he may practically throw away as worthless for his purpose material that to another investigator would be highly important. Hence a person with a theory to test nearly always has to make his own experiments: he looks through the literature in vain, for the men who might easily have observed the phenomenon in which he is interested overlooked the data bearing upon it because their own interest was elsewhere. The result is that the theories which get tested by experiment are usually theories covering a relatively small field; no one person in a lifetime could establish by experiment a complete theory of the motor basis of all mental processes. Yet there is an advantage to be gained by the attempt to construct such a theory: its failures and shortcomings especially may be helpful. The hypotheses developed in this book are not only often impossible to test experimentally, but may even be contradicted by known facts which I have overlooked. And yet I think the labor of writing the book will not have been wholly wasted if here and there a suggestion or a warning is derived which is of use to psychological theory.
The points where I have departed most from what is generally recognized as orthodox psychological doctrine are perhaps the theory regarding the physiological basis of central excitation, and the attempt to utilize, as actual causal mechanisms, certain motor processes which have been neglected by psychological theory as mere incidental phenomena. The most important of these neglected motor processes are the slight actual muscular contractions which accompany all attentive consciousness and are the basis, I believe, of all associative activity. Another motor process to which I have assigned a leading function is the attitude of activity or strain characteristic of strong attention, which I believe actually constitutes the essence of a problem idea.
The first step, evidently, towards working out the hypothesis that all association is association between movements is to describe the association of movements. And therefore the first chapter will briefly survey the way in which movements are combined associatively.