Clark L. Hull was a renowned American psychologist who lived from 1884 to 1952 and was president of the American Psychological Association from 1935 to 1936. This author has gone down in history mainly for his theory of impulse reduction, but this was not his only contribution to psychology and other related sciences.

In this article we will review the biography of Clark L. Hull and his theory of impulse reduction. We will also analyze the influence of this profoundly relevant theorist on the development of behaviorism, and therefore of scientific psychology.

Biography of Clark Leonard Hull

Clark Leonard Hull was born in Akron, a town in New York State, in 1884. According to his autobiography, his father was an aggressive, uneducated man who owned a farm. Hull and his younger brother worked on this farm during his childhood, and often missed school to help with the family business.

At the age of 17, Hull started working as a teacher in a rural school , but soon after he decided that he wanted to study more, so he entered a high school and later the University of Alma, Michigan. Shortly before graduating, he nearly died of typhoid fever.

He later moved to Minnesota to work as an apprentice mining engineer, having specialized in mathematics, physics and chemistry. However, he contracted polio, which caused him to lose the ability to move his leg. During his recovery period, Hull began reading psychology books.

After the illness he returned to work as a teacher and married Bertha Iutzi. He and his wife started attending the University of Michigan, where Hull graduated in Psychology in 1913 . After working for a few years as a professor at the University of Wisconsin, he obtained a position at Yale University, where he worked until his death in 1952.

Main contributions to behaviorism

Hull considered that psychology is a natural science in all its rules, as are physics, chemistry or biology . As such, its laws could be formulated through numerical equations, and secondary laws would exist to explain complex behaviors and even individuals themselves.

Thus, this author sought to determine the scientific laws that explain behavior, and in particular two complex and central aspects of human behavior: learning and motivation. Other theorists, such as Neal E. Miller and John Dollard, worked in the same direction as Hull to find the basic rules that would allow the prediction of behavior.

On the other hand, Hull was the first author to study the phenomena of suggestion and hypnosis using quantitative experimental methodology. In 1933 he published the book “Hypnosis and Suggestibility”, for which he investigated for about 10 years. He considered that these methods were fundamental for the deep understanding of psychology.

Hull proposed in his book “Principles of Behavior” (1943) the theory of impulse, “drive” in the original English. This work had a fundamental influence on the psychology, sociology and anthropology of the 1940s and 1950s, and is still one of the classic reference theories in the history of behaviorism and psychology in general.

Until Hull’s arrival no psychologist had translated the concepts of learning (in particular reinforcement and motivation) using mathematics. This contributed to the quantification of psychology , and consequently to its approach to other natural sciences.

The theory of impulse reduction

Hull proposed that learning is a way of adapting to the challenges of the environment that favours the survival of living beings. He defines it as an active process of forming habits that allow us to reduce impulses, such as hunger, fun, relaxation or sexuality. These can be basic or acquired by conditioning.

According to Hull, when we find ourselves in a “state of need” the impulse, or motivation, to carry out a behaviour that we know from experience to be satisfying increases. For the behaviour to be executed it is necessary that the habit has a certain strength and that the reinforcement that will be obtained by the behaviour motivates the subject .

The formula Hull created to explain the motivation is as follows: Behavioral potential = Strength of habit (number of reinforcements obtained so far) x Impulse (time of deprivation of need) x Incentive value of the reinforcement

However, Hull’s theory was defeated by Edward C. Tolman’s propositional behaviorism, which was more successful because of the introduction of cognitive variables (expectations) and showed that learning can take place without reinforcement. This fact called into question the basis of Hull’s approaches.

Bibliographic references:

  • Hull, C. L. (1943). Principles of Behavior. New York: Appleton-Century-Crofts.
  • Hull, C. L. (1952). Clark L. Hull. A History of Psychology in Autobiography. Worcester, Massachusetts: Clark University Press.