Impulse Reduction Theory: What It Is and What It Explains

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

According to this theory, what promotes the repetition of a behavior, i.e. learning, is its effectiveness 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.

If this theory is now somewhat outdated, it has the merit of having conceptualized behavior in very concrete and mathematical terms, which served as a model for other later theories. SEE MORE IN DEPTH.

    What is the theory of impulse reduction?

    The theory of impulse reduction is a theory of motivation originally posed by Clark Hull in 1943 and later developed by his collaborator Kenneth Spence. This model argues that impulse reduction is the main force behind an organism’s motivation, learning and behavior and would become the main motivational model of the 1940s and 1950s.

    An impulse or “impulse” is defined in this theory as motivation that arises from a psychological or physiological need that must be satisfied to regain an optimal state for the body. It functions as an internal stimulus which motivates the individual to activate himself to satisfy the need which provoked this impulse, by reducing it. We would have innate primary impulses, such as thirst, hunger, and sex, and secondary impulses, which would be learned through conditioning.

    Hull was one of the first theorists to try to create a great theory that would serve to explain all behaviors. He began to develop his theory shortly after starting his work at Yale University, drawing inspiration from many of the great thinkers in behavioral and biological science 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 of the postulation of participating variables, that is, very precisely defined terms that can be used with the help of mathematical symbols. to represent the bear. so Hull he sought to develop a system as scientific as the present in any natural or formal science, Idea taken after reading Isaac Newton and the Greek mathematician Euclid.

    Hull was also influenced by the work of Ivan Pavlov, particularly in taking the principles of conditioning, and from Thorndike he took the idea of ​​the law of effect. In fact, it is from these two major theoretical contributions to the behavioral sciences that Hull seeks 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 is actively working to maintain internal balance. For example, our body constantly regulates its temperature to avoid being either too cold or too hot and thus be able to properly perform its organic functions. Hull believed that behavior was one of the many ways the body had to maintain its balance, but in a more visible way.

      Based on this idea, Hull suggested that motivation, that is, to move to do something, is the result of biological needs. In his theory, Hull used the term “drive” or “impulse” to refer to the state of tension or activation caused by physiological and biological needs. These needs, like thirst, hunger or heat, prompt us to do something. As we find ourselves in an unpleasant, tense state, our body is motivated to resolve or reduce a need.

      With the intention of returning to a pleasant state, humans and also animals are looking for all kinds of ways to meet these biological needs. For example, if we are thirsty we are looking for something to drink, if we are hungry we are looking for food and if we are cold we put on more clothes. According to Hull, if the behavior performed reduces this impulse, this behavior will be repeated in the future in case the same need arises.

      Conditioning and strengthening

      Although Clark Hull is considered a scientist belonging to the neoconductive current, he agrees with most behaviorists that human behavior can be explained in terms of conditioning and reinforcement. Based on what he himself raises with his theory, impulse reduction acts as a reinforcer of a certain behavior.

      Establishing a new behavior that reduces impulses respects the classic stimulus-response relationshipIn other words, when a stimulus and a response are followed by a reduction in need, it increases the likelihood that the same stimulus, if it appears in the future, will generate the same response.

      This reinforcement increases the likelihood that the same behavior will recur in the future if the same need occurs. This makes sense because, in order for an organism to survive in nature, it must adopt behaviors that effectively respond to needs that may arise, learn them and remake them in case the need recurs, because not making it short the risk. not to regain homeostasis and therefore to put oneself in danger.

      The fact that an organism is in danger can be understood as much as it is facing a serious and potential danger (for example, starving) as well as simply feeling a need that it displeases as it remains unresolved ( eg, Ex., Moderate set). Entering a state of need means that the conditions for being able to survive are not met. To be able to satisfy them, the body behaves in a way that reduces this need.

      Deductive mathematical theory of behavior

      As we have discussed, Clark Hull proposed a hypothetico-deductive system for being able to explain behavior, with the intention of developing a system as scientific as that of other sciences such as mathematics and physics. Its aim was to develop a theory of learning that could be expressed in mathematical terms., And for this he established a formula:

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


      • sEr: excitatory potential or probability that the body reacts to one or more stimuli
      • V: Dynamism of the intensity of the stimulus, that is, if certain stimuli exert a great influence on others.
      • D: Momentum strength, determined by the degree of biological deprivation.
      • K: Incentive motivation, or the size or breadth of the goal.
      • J: The delay before the body can seek boosters.
      • SHR: Strength of habit, established by the degree of influence of the above conditioning.
      • slr: conditional inhibition caused by a previous lack of reinforcements.
      • lr: Reactive inhibition or fatigue.
      • Sister: Random error.
      • SLR: Reaction threshold or the smallest amount of reinforcement that will produce learning.

      In Hull’s paradigm, there are three essential elements in any other behavioral theory. And it is a stimulus, or it is an organism and R is a response, in which the paradigm E – O – R. O is affected by I and determines R. When we try to explain the functioning of l organism, to which we have no internal access because it can only be represented as a black box model, if we know which stimuli entered (input) and what responses the body emitted (output), in taking into account the above formula can explain the behavior and learning of O

      Criticisms of the theory

      The pulse reduction theory was very popular in the mid-twentieth century, but today it is somewhat forgotten and there are many reasons for it. Among these we find the exaggerated emphasis on quantifying all behavioral variables, although it is not possible to know everything that influences human behavior besides the fact that the theory had no possibility of generalization. Likewise, it must be said that Hull’s interest in using experimental techniques to treat human behavior had great repercussions and a great influence on later motivational theories.

      However, the main problem with this theory is that cannot explain the importance of secondary reinforcers when reducing impulses. Unlike primary “drives”, such as thirst or hunger, secondary drives are not directly involved in meeting biological needs. An example of this is money, an element that does not directly calm appetite or thirst but allows us to obtain food and drink boosters that directly reduce impulses. The need for money is a powerful source of basic needs reinforcement.

      Another criticism of the model is that the momentum reduction theory does not explain how people, despite being full and homeostatic, sometimes do not reduce their behavioral impulses. For example, on many occasions after eating and satisfied with hunger, we continued to eat more and more, which would be unnecessary behavior because the function of eating is to reduce the craving for hunger.

      Finally, there is the fact that many people voluntarily seek stress, that is to say to break with their homeostasis. Skydiving, jumping or diving to great depths are behaviors that cause us to be tense, the opposite of homeostasis and that make our need for protection and calmness very unfulfilled. The theory cannot explain why people commit such behaviors so contrary to what is instinctive.

      While all of this contributed to Clark Hull’s theory of impulse reduction not being very topical today, it is true that it did help encourage research in psychology from a more scientific perspective. , in addition to being the seed for the development of other theories. on the human behavior that came after. For example, many theories of motivation that emerged during the 1950s and 1960s are based on or had an influence received from Hull’s theory, such as Maslow’s pyramid, which emerged as an alternative to Hull’s theory. Hull model.

      Bibliographical references:

      • Hull, CL (1943). Principles of behavior. New York: Appleton-Century-Crofts.
      • Hull, CL (1952). Clark L. Hull. A history of psychology in autobiography. Worcester, Massachusetts: Clark University Press.
      • Hull, CL (1952). A behavior system. New Haven, CT: Yale University Press.
      • Campbell, B. and Krealing, D. (1953). response force depending on the level of the unit and the degree of reduction of the unit. Journal of Experimental Psychology, 45, 97 – 101.

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