Clark Hull is a pbehavioral psychologist interested in the study of animal learning and concerned with the issue of motivation. Influenced by the theory of evolution. He understood that the needs of the organism were the forces that incited it to action, which must reduce or eliminate these needs. He distinguished between primary impulses and secondary impulses. The primary ones are associated with states of need and have an innate character.
The secondary ones are based on avoidance learning. He developed three theories. The first, developed in the 1930s, consisted of a purely associative theory, in which there were practically no motivational elements. The second was based on the concept of impulse, collected in his work The principles of behavior. He eventually worked on an incentive-based theory of motivation. Miller and Dollard used the concept of acquired impulse to explain motivation in learning.
The experiments of Williams and Perin. Hull relied on the results of these experiments to deduce the characteristics of the impulse. Perin trained four groups of rats to press a lever to obtain food after a 3-hour deprivation, providing different numbers of reinforced trials (5, 8, 30, 70). The resistance to extinction of the response is what is shown in the results graph. Williams trained 4 groups of rats with 22 hours of deprivation and various amounts of reinforced trials. The dependent variable in both experiments was the number of times the animal pressed the lever before the criterion occurred. Hull drew two main conclusions:
- The existence of a regular growth of resistance to extinction depending on the number of trials. It is a continuous and increasing function. The more reinforced trials, the greater the resistance to extinction. The level of execution depends on the motivation. Its rate is equivalent in the two deprivation conditions. The strength of the behavior depended on habit. Habit does not depend on impulse.
- Both curves depend on the deprivation conditions. It is necessary to postulate another construct, the result of which is to strengthen behavior. This construct is the drive. Habit and impulse combine to produce the action potential.
Barry measured the speed of running behavior. Running speed depends on momentum. According to Hull, impulse does not participate in the directionality of behavior, what it does only is provide energy to previously acquired habits. Hull believed that impulse and habits were independent. The habit was produced by a more or less permanent change in the nervous system; the impulse had a rather transitory and passing motivational character. Another question of his theory is that of the independence of impulse and incentive.
It has not been possible to experimentally verify that impulse and incentive are truly independent. Contribution of Spencer to Hull’s theory Hull defended the theory that reinforcement reduced tension. Spence never did. Hull began by pointing out that incentives influence the strength of habit and then went on to propose that they influenced performance. Spence always understood motivation as an incentive. Spence used classical and instrumental learning. The first is important because it is where anticipatory goal responses are produced.
The instrumental is directed by the incentive, as it is what directs the execution of the instrumental behavior. He considered that the generalized impulse was multiplied by the force of habit. He recognized the value of incentives. Impulse and incentive have a additive effect. The sum of impulse and incentive is multiplied by the force of habit to give rise to the action potential. He has recognized the role of inhibition based on reward anticipation. The individual becomes frustrated when there is a lack of reward. The formula for the action potential is: EPR = f(EHR X – In)
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