Hull’s Systematic Behavior Theory
Introduction;
To understand the Hull’s theory we must trace back the historical development of philosophical implications and chief assumptions of the behaviorist theories, historically we find two most prominent families of learning theories.
One is Stimulus-Response association, and other is Gestalt field theories.
Hull’s theory basically belongs to the first family of learning theories, i-e Stimulus-response association. In the beginning of 20th century a new form of association became popular which was non-mentalist, or physiological association. The chief exponents were John B. Watson and Edward L. Thorndike.
Watson psychology was known as behaviorism while Thorndike psychology was called connectionism, although the psychological systems of Thorndike and Watson no longer advocated in their original form, but many contemporary psychologists have orientations sufficiently similar to theirs, are called Neo Behaviorist. Some leading contemporary behaviorists are E.R Guthrie, C.L Hull, B.F Skinner and K.W Spence.
Emergence of S.R Association;
The early associationists were interested in mental phenomena (John Calvin, J. Edwards). In contrast modern associationism tends to be rooted in a different kind of interest i-e the behavior of bodies. During the first half of nineteenth century experimental psychology got it’s started with in experimental physiology. For instance physiologist Bell Muller made experiments on working of nervous system in seeing and hearing, Wilhelm Wundt was trained in medicine. He turned to medical, to physiology and from physiology to psychology. As interest in bodily functioning become apparent among many psychologists late in 19th century. This group of physiological psychologist argued that psychology could become a true science only if it switched its focus to bodily process. Thus they begin to focus their attention on objects or events which could be observed with the five senses be studied in the same manner by any number of trained investigators and led to uniform conclusion.
To a growing number of psychologist the only logical alternative to the method of introspection was to focus on observable form of behavior such behavior include not only bodily movement as seen by observer, watching a subject but also internal physical processes related to overt bodily behavior.
Gradually a large number of psychologists had come to feel that psychology in time could be come as scientific as physics. A few of person who contributed to the development of physiological psychology was Marshal Hall (1790¬¬¬––1857), worked on neural basis of reflex behavior, Pierre Flourens (1794––1867) demonstrated that different parts of the nervous system have different functions and identified the function of each part. Some of notable animal learning experiments of the late 19th and early 20th centuries were conducted by Russian psychologist Ivan Petrovich Pavlov (1849––1936). Pavlov put food before a hungry dog and sounded a bell, he found that if this procedure repeated for several times the sound alone would cause the dog to salivate.
Thorndike animal experiments, making use of chickens, dogs, and cats were possibly more comprehensive than Pavlov’s. Thorndike’s famous laws of learning were derived mainly from his interpretation of how cats behave when placed in a cage from which they do not know how to escape until they learn.
Watson much more strongly, than Thorndike, felt the need to base psychology exclusively on the concept of physics and chemistry.
Watson drew heavily upon Pavlov’s work and became convinced that learning was as Pavlov described it namely, a process of building condition reflexes through substitution of one stimulus for another. Watson and other “pure behaviorists” rejected certain Thorndike’s ideas like “mental units”, “satisfaction” and “annoyance” which seemed to be mentalistic concepts and should be disregarded in a truly scientific psychology. Thus Watson confined his study to only those aspects of animal life which were sufficiently overt to make possible highly objective observation and measurement of them.
The Emergence of Neo-Behaviorists;
It was observed that the precise nature of neural mechanisms was largely irrelevant to an understanding of learning. A strong interest in neural physiology and the physical mechanics of S––R linkages was developed and the behavior of the organism became the focus of the analyses, instead of neural mechanism behind it.
Studies were carried out to show how S’s and R’s are linked rather than the precise operation of the physiological mechanism which lies between the S’s and R’s. this gave birth to the term Neo-Behaviorists.
Classification of Neo-Behaviorists
The neo-behaviorists may be divided in to three groups,
1. Conditioning independent of reinforcement
2. Conditioning governed by principles of reinforcement
3. The two factor theory.
C.L Hull belong the second group how focus on conditioning governed by principles of reinforcement and is known as “Deductive Behaviorism or Reinforcement theory”.
About hull 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 inderlying 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.
His 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).
