What is drive theory? |

Introduction

One goal of science is to understand, predict, or manipulate natural events. A scientist may start by observing an event of interest and measuring it as precisely as possible to detect any changes. In experimental research, scientists systematically manipulate various other events to see whether the event of interest also changes. In survey research, different events are measured to see whether they vary with the event of interest. Understanding is achieved when the relationship between the event of interest (the dependent variable) and other events (independent variables) is established. One can then predict or manipulate the event of interest. A theory provides a guideline to organize the variables into a system based on common properties. To a psychologist, the dependent variable is the behavior of all animals and humans, and the independent variables (also called determinants) may be any other variable related to behaviors. Psychological research aims to discover the determinants of a certain behavior, some of which are motivational variables. The field of motivation
examines why a particular behavior occurs, why it is so strong, and why it is so persistent.

A drive is a process related to the source of behavioral energy originating from within the body that is created by disturbances in homeostasis (a state of systemic equilibrium). A homeostatic imbalance creates a state of need for certain stimuli from the environment that can restore the balance. For example, abnormal body temperature and hyperosmolality of the body fluid (electrolyte concentration outside cells that is higher than that of the intracellular fluid, resulting in cell dehydration) are disturbances in homeostasis. The homeostatic balance can be restored through two means: physiological and behavioral. Physiological means such as vasodilation, sweating, and panting serve to reduce body temperature, while concentration of electrolytes in the urine by the kidneys reduces hyperosmolality. Behavioral means such as taking off clothes, turning on an air conditioner, and drinking cold liquid lower body temperature; drinking water would also result in reduction of hyperosmolality. One may examine a case of homeostatic imbalance in detail to illustrate how the two means function to restore the balance.

When the body fluid volume is reduced (hypovolemia) because of loss of blood or of body fluid due to intense sweating, the body responds immediately by vasoconstriction, reducing urine volume (through vasopressin release), and conserving sodium (through aldosterone release). Those are physiological means that will restore the blood pressure and prevent circulatory failure. Eventually, however, the body must get back the lost fluid from the environment via behavior (seeking water and drinking) to achieve long-lasting homeostasis. The physiological means are immediate and effective, but they are only stopgap measures. Behavior is the means by which the animal interacts with its environment to get back the lost resource.

Drive, Reinforcement, and Learning

The concept of drives is very important to the theories of Clark L. Hull, a neo-behaviorist. According to Hull, a drive has at least two distinct functions as far as behavioral activation is concerned: without drives there could be no reinforcement and thus no learning, because drive reduction is the reinforcement; and without drives there could be no response, for a drive activates behavioral potentials into performance. Drive theory maintains that a state named “drive,” or D, is a necessary condition for behavior to occur, but D is not the same as the bodily need. D determines how strongly and persistently a behavior will occur; it connects the need with the behavior. This distinction between need and drive is necessary because while the state of need serves as the source of behavior, the intensity of behavior is not always related to the intensity of need. Need can be defined as a state of an organism attributable to deprivation of a biological or psychological requirement, related to a disturbance in the homeostatic state.

There are cases in which the need increases but behavior does not, or in which the need remains but behavior is no longer manifested. Prolonged deprivation, for example, may not result in a linear or proportional increase in behavior. A water-deprived animal may stop drinking even before cellular dehydration is restored to the normal state; the behavior is changing independent of homeostatic imbalance. Cessation of behavior is seen as being attributable to drive reduction.

Hull uses D to symbolize drive and sHr (H is commonly used to denote this, for convenience) to symbolize a
habit that consists of an acquired relationship between stimulus (S) and response (R). It represents a memory of experience in which certain environmental stimuli and responses were followed by a reward. An effective reward establishes an S-R relationship; the effect is termed reinforcement. One example of an H would be an experience of maze stimuli and running that led to food. H is a behavioral potential, not a behavior. Food deprivation induces a need state that can be physiologically defined; then D will energize H into behavior. The need increases monotonically with hours of deprivation, but D increases only up to three days without food. A simplified version of the Hullian formula for a behavior would be “behavior = HD,” or “performance = behavioral potential energizer.” The formula indicates that learning, via establishing behavioral potential, and D, via energizing the potential, are both necessary for performance to occur. This is a multiplicative relationship; that is, when either H or D is zero, a specific performance cannot occur.

Role of Freud’s “Id”

In his psychoanalytical approach to behavioral energy, Sigmund Freud
proposed that psychic energy is the source of human behaviors. The id
is the reservoir of instinctual energy presumed to derive directly from the somatic processes. This energy is unorganized, illogical, and timeless, knowing “no values, no good or evil, no morality,” according to Freud in 1933. The id operates according to the pleasure principle, using the primary process to discharge its energy as soon as possible, with no regard for reality. When the discharge is hindered by reality, however, the ego handles the situation according to the reality principle, using a secondary process to pursue realistic gratification. The ego mediates between the id on one hand and reality on the other.

Freud thus conceptualized the id to be the energy source and the ego to manage behavior in terms of reality. Learning is manifested in the way the ego manages behavior for gratification under the restriction of the environment and the superego. In this model, the drive is seen as the energizer of behavior. The similarity between the Freudian and Hullian concepts of drive is obvious. Food deprivation would generate homeostatic imbalance, which is the somatic process, and the need, which is similar to the energy of the id. The organism cannot obtain immediate gratification because of environmental constraints on acquiring food, so behavior is generated to negotiate with the environment. Drive is much like the ego, since it energizes the behavioral potentials into behaviors to seek reality gratification, which is equivalent to drive reduction. The concept of pleasure and behavioral changes commonly appears in various theories that incorporate a subtle influence of Freudian thought.

Deprivation and Incentive Motives

In one classic experiment, Carl J. Warden studied the persistence of behavior as a function of various sources, including the strength of a drive, using an apparatus called a Columbia obstruction box. He demonstrated that a rat without food would cross an electrified grid to reach a goal box that held food. When the rat was immediately brought back from the goal box to the start box, it would cross the grid again and again. The number of grid crossings was positively related to the number of days without food for up to three days. From the fourth day without food, however, the number of crossings slowly decreased. When baby rats were placed in the goal box, a mother rat would cross the grid repeatedly. When a male or female rat was placed in the goal box, a rat of the opposite sex would cross repeatedly. The number of crossings by the male rat was positively related to the duration it spent without a female companion.

These animals were all manifesting the effect of different drives: hunger, maternal instinct, and sex. It was shown that the maternal drive was associated with the greatest number of crossings (twenty-two times in twenty minutes), followed by thirst (twenty times), hunger (seventeen), female sex drive (fourteen), male sex drive (thirteen), and exploration (six). Warden demonstrated that various internal forces, created by deprivation and hormonal state, and external forces, created by different goal objects, together determine the grid-crossing behavior. The level of deprivation induces drive motivation; the reward in the goal box induces incentive motivation. In this example, the focus is on drive motivation.

If one were to place a well-trained rat into a maze, it might or might not run to the goal box. Whether it would run, how fast it would run, and how well (in terms of errors) it would run would depend on whether the subject were food deprived. With food deprivation, the well-trained rat would run to the goal box with few errors. If it had just been fed, it would not run; it would simply wander, sniff at the corner, and go to sleep. The environmental stimulus (the maze) is the same; the rat’s behavior is different because the internal force—the drive created by food deprivation—is different. A need state produces D, and D triggers behavior. The behavior that will occur is determined jointly by the past experience of learning, which is termed H, and by stimuli, S, from the environment. An inexperienced rat, without the H of maze running, will behave differently from a well-trained rat in a maze. D is an intervening variable: It connects need and behavior, so one must consider both the source (need) and the consequence (behavior) to define D. When D is zero, there will be no maze running, no matter how well trained the rat is. On the other hand, if there is no H (training), the proper maze-running behavior will not occur, no matter how hungry the rat is. An animal must be exposed to a maze when hungry to learn to negotiate the various turns on the way to the goal box containing food. Without food deprivation (and the resultant D), the animal would not perform even if it could; one cannot tell whether an animal has the knowledge to run the maze until one introduces a D variable. H is a potential of behavior, and D makes the potential into the observable reality of performance. Motivation turns a behavior on.

These ideas can be applied to countless real-life examples. If a person is not very good at playing tennis (has a low H), for example, no matter how motivated (high D) he or she is, that person will not be able to beat a friend who is an expert at the game. If a person is very good at tennis (high H) but does not feel like playing (low D), perhaps because of a lack of sleep, he or she will not perform well. The same situation would apply to taking a test, delivering a speech, or running a marathon.

Puzzle-Box Learning

In another experiment involving drive, Edward L. Thorndike
put a cat into a puzzle box. The cat attempted to get out via various behaviors (mewing, scratching, and so on). By chance, it stepped on a plate that resulted in the door opening, allowing the cat to escape. The cat was repeatedly returned to the box, and soon it would escape right away by stepping on the plate; other, useless behaviors were no longer manifested. The source of D in this case was the anxiety induced by confinement in the box, which could be measured by various physiological changes, such as heart rate and hormonal levels. Escaping makes the anxiety disappear, and D is reduced. D reduction results in an increase in the probability that the behavior immediately preceding it (stepping on the plate) will recur. Thorndike describes this puzzle-box learning as trial and error, implying a blind attempt at various means of escape until one happens to work. He states that a “satisfying effect” will create repetition, calling this the law of effect; the essence of the satisfying effect appears to be drive reduction. A five-stage learning cycle, then, consists of need, drive, behavior, drive reduction, and behavior repetition.

Central Motive State

The question of how a habit (H) is formed and how it is stored in the brain is a lively research topic in the psychobiology of learning, memory, and cognition, as well as in neuropsychology, which deals with learning deficit and loss of memory. Drive and reinforcement are important variables that determine whether learning will succeed and whether past learning will be manifested as behaviors. Research on hunger and thirst forms one subfield of psychobiology.

If D is the common energizer of various behaviors, then all sources of D—hunger, thirst, sex, mothering, exploration—should have something in common physiologically. The so-called central motive state is hypothesized to be such a state. It is known that arousal is common to the sources of D. Research involves biological delineation of the sources of D; researchers are studying the mechanisms of hunger, for example. There has been insufficient attention paid to the physiological processes by which hunger may motivate various behaviors and by which drive reduction would serve as a reinforcement in learning. Extreme lack of motivation can be seen in some depressed and psychotic patients, which results in both a lack of new learning and a lack of manifesting what is already known. The neuronal substrates of this “lack of energy” represent one problem under investigation in the area of drive and motivation.

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