Clark L. Hull: biography, theory and contributions.

One of the most studied behaviorists in Psychology faculties.

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. and was president of the American Psychological Association between 1935 and 1936. This author has gone down in history mainly for his theory of drive 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 drive reduction. We will also analyze the influence of this deeply relevant theorist in the development of behaviorism, and therefore of scientific psychology.

• Recommended article: "Behaviorism: history, theories and main authors".

Biography of Clark Leonard Hull

Clark Leonard Hull was born in Akron, a town in the state of New York, in 1884. As he recounts in his autobiography, his father was an aggressive, uncultivated man who owned a farm. Hull and his younger brother worked on the farm during their childhood, and often missed school to help in the family business.

At the age of 17, Hull began working as a teacher in a rural school, but soon after decided he wanted to study for a degree.Soon after, he decided he wanted to study further, so he entered high school and then Alma University in Alma, Michigan. Shortly before graduating he nearly died of typhoid fever.

He later moved to Minnesota to apprentice as a mining engineer, since he had majored in mathematics, physics and chemistry. However, he contracted polio; as a result of this disease he lost the ability to move one leg. During the recovery period Hull began to read psychology books.

After his illness he returned to work as a teacher and married Bertha Iutzi. He and his wife began attending the University of Michigan, where Hull graduated with a degree 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 psychology to be a full-fledged natural science, like 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 predicting 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 researched for about 10 years. He considered these methods to be 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 psychology, sociology and anthropology in the 1940s and 1950s, and remains 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 rapprochement with other natural sciences.and consequently to its rapprochement with other natural sciences.

The theory of drive reduction

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

According to Hull, when we are in a "state of need" the impulse, or motivation, to perform a behavior that we know from experience satisfies it increases. For the behavior to be executed it is necessary that the habit has a certain strength and that the reinforcement that will be obtained by the behavior motivates the subject..

The formula that Hull created to explain motivation is the following: Behavioral potential = Habit strength (number of reinforcements obtained so far) x Impulse (time of deprivation of the 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 demonstrated that there can be learning without the need for reinforcement. This fact called into question the basis of Hull's approach.