Impulse reduction theory: what is it and what does it explain?

A summary of the impulse reduction theory, developed by Hull and Spence.

Impulse reduction theory is a model which became popular in the middle of the last century and was conceptualized by Clark Hull to explain how behavior, learning and motivation were related.

According to this theory, what makes us repeat a behavior, i.e. learning, is how effective it is in reducing an internal need such as thirst or hunger. The basis of this theory is that impulse reduction is the main force behind motivation.

While this theory is somewhat outdated today, it does have the merit of having conceptualized behavior in very concrete and mathematical terms, which served as a model for later theories. Let's take a closer look.

What is the impulse reduction theory?

The theory of impulse reduction is a theory of motivation originally put forward by Clark Hull in 1943 and later developed by his collaborator Kenneth Spence.. This model holds that drive reduction is the primary force behind an organism's motivation, learning, and behavior and would become the leading motivational model of the 1940s and 1950s.

An impulse or "drive" is defined in this theory as the motivation that arises due to a psychological or physiological need that must be satisfied in order to regain an optimal state for the organism.. It functions as an internal stimulus that motivates the individual to activate himself to satisfy the need that has provoked that drive, reducing it. We would have primary drives that are innate, such as thirst, hunger and sex, and secondary drives, which would be learned through conditioning.

Hull was one of the first theorists to try to create a grand theory that could explain all behavior.. He began developing his theory shortly after he started working at Yale University, drawing inspiration from a number of great thinkers in the behavioral and Biological sciences such as Charles Darwin, Ivan Pavlov, John B. Watson, and Edward L. Thorndike.

The theory of impulse reduction was developed as a hypothetico-deductive system in psychology, which consisted in the postulation of participating variables, that is, very precisely defined terms that could be used using mathematical symbols to represent them. Thus Hull The idea was to develop a system as scientific as that present in any natural or formal science, an idea taken after reading Isaac Newton and the Greek mathematician Euclid.Hull was influenced by the work of Isaac Newton and the Greek mathematician Euclid.

Hull was also influenced by the work of Ivan Pavlov, especially taking the principles of conditioning, and from Thorndike he took the idea of the law of effect. In fact, it is from these two great theoretical contributions to the behavioral sciences that Hull tried to integrate a new system by creating his theory of impulse reduction.

Homeostasis and learning

Clark Hull based his theory on the concept of homeostasis, i.e., the idea that an organism actively works to maintain internal balance. For example, our body constantly regulates its temperature to avoid being too hot or too cold and thus be able to carry out its organic functions properly. Hull thought that behavior was one of the many ways the body maintained its balance, only in a more visible way.

Based on this idea, Hull suggested that motivation, i.e., moving to do something, is the result of biological needs. In his theory, Hull used the term "drive" to refer to the state of tension or activation caused by physiological and biological needs. These needs, such as thirst, hunger or heat seeking, drive us to do something. As we find ourselves in an unpleasant state, being in tension, our organism is motivated to resolve a need or reduce it.

With the intention of returning to a pleasant state, humans, and animals too, look for all kinds of ways to satisfy these biological needs. For example, if we are thirsty we look for something to drink, if we are hungry we look for food, and if we are cold we put on more clothes. According to Hull, if the behavior performed works to reduce that drive, that behavior will be repeated in the future if the same behavior occurs. in the future if the same need arises.

Conditioning and reinforcement

Although Clark Hull is considered a neobehaviorist scientist, he agrees with most behaviorists in considering that human behavior can be explained in terms of conditioning and reinforcement. According to his theory, the reduction of impulses acts as a reinforcer of a given behavior.

The establishment of a new behavior that reduces urges respects the classic stimulus-response relationshipthat is, when a stimulus and a response are followed by the reduction of the urge, this increases the probability that the same stimulus, if it appears in the future, will generate the same response.

This reinforcement increases the probability that the same reward will occur again in the future if the same need occurs. This makes sense since, in order for an organism to survive in nature, it must perform behaviors that effectively solve the needs that may arise, learn them and do them again in case the need arises again, since otherwise it runs the risk of not recovering homeostasis and, therefore, putting itself in danger.

That an organism is in danger can be understood as both a serious and potential danger (p. e.g., dying of starvation) as simply feeling a need that causes displeasure the longer it goes unresolved (e.g., moderate thirst). Entering a state of need means that the requirements for survival are not being met. In order to satisfy them, the organism behaves in a way that focuses on reducing that need..

Deductive mathematical theory of behavior

As we mentioned, Clark Hull proposed a hypothetical-deductive system to explain behavior, with the intention of developing a system as scientific as that of other sciences such as mathematics and physics. His aim was to develop a theory of learning that could be expressed in mathematical terms.and to this end he put forward a formula:

sEr = V x D x K x K x J x sHr - sIr - Ir - sOr - sLr.

Where:

• sEr: excitatory potential, or the probability that the organism makes a response (r) to a stimulus (s).
• V: Dynamism of stimulus intensity, meaning that if some stimuli exert great influence on others.
• D: Strength of the impulse, determined by the degree of biological deprivation.
• K: Motivational incentive, or the size or magnitude of the goal.
• J: The delay before the organism is able to seek reinforcers.
• sHr: Strength of habit, established by the degree of influence of prior conditioning.
• slr: Conditioned inhibition caused by previous lack of reinforcers.
• lr: Reactive inhibition or fatigue.
• sOr: Random error.
• sLr: Reaction threshold or the smallest amount of reinforcement that will produce learning.

In Hull's paradigm there are three indispensable elements in any other behaviorist theory. E, that is stimulus, O that is organism and R that is response, being the paradigm E - O - R. O is affected by E and determines R. When trying to explain the functioning of the organism, to which we have no internal access since it can only be represented as a black box model, if we know what stimuli have entered (input) and what responses the organism has emitted (output), taking into account the above formula we will be able to explain O's behavior and learning.

Criticisms of the theory

The theory of impulse reduction was very popular in the middle of the 20th century, however today it is somewhat forgotten and the reasons behind it are numerous. Among these we find the exaggerated emphasis on quantifying all behavioral variables, although it is not possible to know everything that influences human behavior and the theory lacked generalizability. It should also be said that Hull's interest in using experimental techniques to approach human behavior has had great repercussions and influence on later motivational theories.

However, the main problem with this theory is that it is unable to explain the importance of secondary reinforcers in explaining the importance of secondary reinforcers in the behavioral process. it cannot account for the importance of secondary reinforcers in reducing impulses.. Unlike primary drives, such as thirst or hunger, secondary drives are not directly involved in the satisfaction of biological needs. An example of this is money, an element that does not directly quench hunger or thirst but does allow us to obtain food and drink reinforcers that do directly reduce drives. The need to obtain money acts as a powerful source of basic need reinforcers.

Another criticism of the model is that the theory of drive reduction does not explain how people, despite being satiated and finding homeostasis, sometimes do not reduce their behavioral impulses.. For example, on many occasions, after having eaten and having our hunger satisfied, we continue to eat more and more, which would be an unnecessary behavior since the function of eating is to reduce the need for hunger.

Finally, there is the fact that many people voluntarily seek tension, i.e., to break their homeostasis.. Parachute jumping, bungee jumping or deep diving are behaviors that lead us to be in tension, just the opposite of homeostasis and make our need to be protected and calm very unsatisfied. The theory cannot explain why people commit these types of behaviors so contrary to what is instinctive.

Although all this has contributed to the fact that Clark Hull's theory of impulse reduction is not very current today, it is true that it has helped to promote research in psychology from a more scientific perspective, as well as being the seed for the development of other theories on human behavior that came later. For example, many theories of motivation that emerged during the 1950s and 1960s are based on Hull's theory or had some influence received from it, as is the case of Maslow's pyramid, which emerged as an alternative to Hull's model.

Bibliographical 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.
• Hull, C. L. (1952). A behavior system. New Haven, CT: Yale University Press.
• Campbell, B., & Krealing, D. (1953). response strength as a function of drive level and amount of drive reduction. Journal of Experimental Psychology, 45, 97 - 101.