CLARK HULL 1884-1952: A PIONEER IN EXPERIMENTAL HYPNOSIS

1. CLARK HULL: PSYCHOLOGY HISTORY (1884 - 1952): JANA SCHROCK (MAY 1999)

2. FOREWORD BY ERNEST R. HILGARD :
1. CLARK HULL: PSYCHOLOGY HISTORY (1884 - 1952): JANA SCHROCK (MAY 1999)
Clark Hull grew up handicapped and contracted polio at the age of 24, yet he became one of the great contributors to psychology. His family was not well off so his education had to be stopped at times. Clark earned extra money through teaching. Originally Clark aspired to be a great engineer, but that was before he fell in love with the field of Psychology. By the age of 29 he graduated from Michigan University. When Clark was 34 when he received his Ph.D. in Psychology at the University of Wisconsin in 1918. Soon after graduation he became a member of the faculty at the University of Wisconsin, where he served for 10 years. Although one of his first experiments was an analytical study of the effects of tobacco on behavioral efficiency, his life long emphasis was on the development of objective methods for psychological studies designed to determine the underlying principles of behavior.
Hull devoted the next 10 years to the study of hypnosis and suggestibility, and in 1933 he published Hypnosis and Suggestibility, while employed as a research professor at Yale University. This is where he developed his major contribution, an elaborate theory of behavior based on Pavlov's laws of conditioning. Pavlov provoked Hull to become greatly interested in the problem of conditioned reflexes and learning. In 1943 Hull published, Principles of Behavior, which presented a number of constructs in a detailed Theory of Behavior. He soon he became the most cited psychologist.
THEORY: Hull believed that human behavior is a result of the constant interaction between the organism and its environment. The environment provides the stimuli and the organism responds, all of which is observable. Yet there is a component that is not observable, the change or adaptation that the organism needs to make in order to survive within it's environment. Hull explains, "when survival is in jeopardy, the organism is in a state of need (when the biological requirements for survival are not being met) so the organism behaves in a fashion to reduce that need" ( Schultz & Schultz, 1987, p 238). Simply, the organism behaves in such a way that reinforces the optimal biological conditions that are required for survival.
Hull was an objective behaviorist. He never considered the conscious, or any mentalistic notion. He tried to reduce every concept to physical terms. He viewed human behavior as mechanical, automatic and cyclical, which could be reduced to the terms of physics. Obviously, he thought in terms of mathematics, and felt that behavior should be expressed according to these terms. "Psychologist must not only develop a thorough understanding of mathematics, they must think in mathematics" (Schultz & Schultz, 1987, p 239). In Hull's time three specific methods were commonly used by researchers; observation, systematic controlled observation, and experimental testing of the hypothesis. Hull believed that an additional method was needed, - The Hypothetico Deductive method. This involves deriving postulates from which experimentally testable conclusions could be deduced. These conclusions would then be experimentally tested.
Hull viewed the drive as a stimulus, arising from a tissue need, which in turn stimulates behavior. The strength of the drive is determined upon the length of the deprivation, or the intensity / strength of the resulting behavior. He believed the drive to be non-specific, which means that the drive does not direct behavior rather it functions to energize it. In addition this drive reduction is the reinforcement. Hull recognized that organisms were motivated by other forces, secondary reinforcements. " This means that previously neutral stimuli may assume drive characteristics because they are capable of eliciting responses that are similar to those aroused by the original need state or primary drive" (Schultz & Schultz, 1987, p 240). So learning must be taking place within the organism.
Hull's learning theory focuses mainly on the principle of reinforcement; when a S-R relationship is followed by a reduction of the need, the probability increases that in future similar situations the same stimulus will create the same prior response. Reinforcement can be defined in terms of reduction of a primary need. Just as Hull believed that there were secondary drives, he also felt that there were secondary reinforcements - " If the intensity of the stimulus is reduced as the result of a secondary or learned drive, it will act as a secondary reinforcement" ( Schultz & Schultz, 1987, p 241). The way to strengthen the S-R response is to increase the number of reinforcements, habit strength.
Clark Hull's Mathematico Deductive Theory of Behavior relied on the belief that the link between the S-R relationship could be anything that might effect how an organism responds; learning, fatigue, disease, injury, motivation, etc. He labeled this relationship as "E", a reaction potential, or as sEr. Clark goal was to make a science out of all of these intervening factors. He classified his formula sEr = (sHr x D x K x V) - (sIr + Ir) +/- sOr as the Global Theory of Behavior. Habit strength, sHr, is determined by the number of reinforces. Drive strength, D, is measured by the hours of deprivation of a need. K, is the incentive value of a stimulus, and V is a measure of the connectiveness. Inhibitory strength, sIr, is the number of non reinforces. Reactive inhibition, Ir, is when the organism has to work hard for a reward and becomes fatigued. The last variable in his formula is sOr, which accounts for random error. Hull believed that this formula could account for all behavior, and that it would generate more accurate empirical data, which would eliminate all ineffective introspective methods within the laboratory (Thomson, 1968). Although Hull was a great contributor to psychology, his theory was criticized for the lack of generalizability due to the way he defined his variables in such precise quantitative terms. "Thus, Hull's adherence to a mathematical and formal system of theory building is open to both praise and criticism" (Schultz & Schultz, 1987, p 242).
Time Line
1884 Hull was born
1918 Received Ph.D. from University of Wisconsin
19 publication of the literature on tests and measurements 19 Becomes research Professor at Yale
193 Hypnosis and Suggestibility , published
1940 Mathematico - Deductive Theory of Rote Learning: A study in Scientific Methodology was published.
19 Principles of Behavior was published
1951 The Essentials of Behavior was published
1952 A Behavior System was published
1952 Hull died

2. FOREWORD TO "HYPNOSIS AND SUGGESTIBILITY": APPLETON-CENTURY-CROFTS: NY: COPYRIGHT 1933 BY ERNEST R. HILGARD (1961 EDITION : Professor Clark L. Hull (1884-1952) was an ardent behaviorist, but an unusual one. Instead of closing his eyes to phenomena that might seem to others to be the very epitome of the subjective -whether the trance state within hypnosis or matters such as foresight and purpose-he set out to show that he could treat them by his objective methods. This book was one of the diverse products of this ingenious experimenter and theoretician, working first at the University of Wisconsin, and later at Yale University. His other books, on aptitude testing (1928) and on learning (1940, 1943, 1951, 1952), were all of quality and significance, and this book on hypnosis stands up well alongside them.
It was an important event in the checkered story of hypnosis when this book, so methodologically sound, so full of experimental data, made its appearance. Hypnosis had always been a bit on the fringe-known too often as entertainment, or exploited by those who wished to demonstrate some mysterious or uncanny functioning of the human mind-and here at last was a matter-of-fact laboratory investigation. After more than 30 years Hull's findings hold up very well indeed, and it is good to have his book widely available in accessible form.
Although devoted largely to the experiments of his own and his students and collaborators, these investigations are placed in the context of history, and the historical material is painstaking and accurate. It is interesting, for example, to see Hull's concern over Alfred Binet, a distinguished investigator (whose name we know in connection with intelligence tests) because Binet permitted the authority of Charcot to make him accept the bizarre results of some experiments, results which could only have been obtained due to experimenter bias.
Hull's own biases did not lead him to mistake his own fancies for data, and all experiments are beautiful illustrations of experimental design and objectivity of interpretation. Despite his courage in attacking a range of problems not always congenial to the objectivist, Hull's behaviorism led him to an overemphasis (xiii) upon phenomena of movement, learning, and retention, for which methods of measurement were available, and to underplay such phenomena as positive and negative hallucinations. To his credit it must be said that he recognized the broad range of the standard phenomena of hypnosis as genuine, and neglect does not mean denial. Despite an interest in individual differences that had led to an earlier book on aptitude testing, the material on differences in susceptibility is fragmentary, and because of his lack of interest in personality dynamics there is almost none of the clinician's "feel" for the interpersonal aspects of hypnosis. But there is so much here that a few omissions can be excused.
Ever since the days of Mesmer, hypnosis has had a rough and undulating history of acceptance and rejection. There are signs now of greater acceptance, such as recommendations by both the American and British Medical Associations that hypnosis be taught in medical schools, and the establishment with the blessing of the American Psychological Association of an American Board of Examiners in Psychological Hypnosis, issuing certificates in both experimental and clinical hypnosis. Those who are today finding it easier to do investigatory work in the field without being considered "far out," and to use hypnosis in their therapeutic work without being ostracized owe some of this acceptance to Clark L. Hull and his collaborators for having carried out the work reported in this book. Hull, in the conclusion to the book, noted some of the difficulties in working in this area:
Too many of the works on the subject in the past have fallen short of the scientific ideal. Doubtless many things have contributed to this weakness, but surely a major factor must be the inherent difficulty of the problems involved, the fundamental elusiveness of the phenomena, and the consequent subtlety necessary in the experimental controls. These difficulties are so great that to enter seriously on a program of investigation in this field is a little like tempting fate; it is almost certain to court disaster. Small wonder that orthodox scientists have usually avoided the subject! Yet each generation may be expected in the future, as in the past, to produce a few rash souls who will not only risk the danger of making scientific errors but will also have the courage to brave the semi-superstitious fears of the general public and the uneasy suspicions of their orthodox scientific brethren. It is to them that the present work is really addressed (page 403).
Because the problems of hypnosis lie at the very heart of human planfulness and self-control, as well as the relinquishing of control to another, because its methods permit explorations of significant reality distortions, hypnotic experimentation holds the promise of broadening our understanding of personality functioning generally, apart from the intrinsic interest in hypnotic phenomena themselves.
Hull, in the privacy of his notebook diaries, felt that this book was a good one. After expressing some concern that he might become stigmatized for working on hypnosis, he goes on to say:
I believe, however, that the book itself has been worth doing from the point of view of the advancement of science. I believe that it is an important contribution, that it may mark a new epoch in that form of experimentation, and that it will be read and quoted for a long time, possibly a hundred years.1
The book is well along on its first hundred years without losing any of its freshness. It still stands as a model of clarity and objectivity in the approach to what remain even today puzzling and unsolved problems. ERNEST R. HILGARD (1961 Edition)