Book Cover  Psychology: Science & Understanding     Barry D. Smith
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Chapter 12: Motivation (Smith 1e)


Chapter Overview

Chapter 12 addresses the question why people behave the way they do. Whereas some behaviors are motivated by physiological needs, the motivations underlying other behaviors are more difficult to explain. The author of the text defines motivation as referring to processes that energize and maintain goal-directed behavior. Motives are defined as the needs and desires the goal-directed behavior attempts to satisfy. The author of the text acknowledges that there is no universal agreement on the definition of motivation. Motivation is closely linked to the topic of emotion, which will be covered in chapter 13.

Chapter 12 contains five major sections: (1) "Theories of Motivation," (2) "Hunger Motivation," (3) "Sexual Motivation," (4) "Achievement and Social Motivations," and (5) "The Neurophysiology of Motivation."

The first section ("Theories of Motivation") begins by stating that the motivational issues addressed by theories of motivation can be summarized in three major questions: (1) What are the major motive systems and how do they motivate behavior? (2) How do these systems relate to each other? and (3) What are the underlying psychological, environmental, and physiological causes of motivated behavior and how do they interact? Seven theories of motivation are covered: (1) instinct theory; (2) drive theory; (3) incentive theory; (4) optimal arousal theory; (5) Maslow's need hierarchy; (6) cognitive theory; and (7) evolutionary theory. According to instinct theory, some behaviors are driven by instincts, which are innate, biological motives that are present in all members of a species and are expressed in a consistent way. William McDougall hypothesized that human behavior is also motivated by instincts, and he compiled a long list of automatic, inborn behavior patterns. Instinct theories fell into disrepute because they could not explain the variability in human behavior that was influenced by learning. Today, instinct theory takes the form of ethology, the study of the species-specific behaviors of animals, including humans, in their natural settings.

Drive theory, developed by Robert S. Woodworth and Clark Hull, proposes that the concept of a drive, one of the most widely used concepts in theories of motivation, denotes a condition of arousal or tension that motivates behavior aimed at reducing that tension. Drive theories typically hypothesize that a set of physiological survival drives, including hunger, thirst, sleep, pain, and sex, motivate behavior. Hull and other drive theorists have suggested that a drive results from the activation of a need or from intense stimuli. The deficiency or stimulus disrupts homeostasis, a state of equilibrium or stability that the body strives to maintain. Drive theory continues to guide a considerable amount of research. Incentive theory accounts for individual differences in behavior by assessing the value an incentive has for a specific individual. An incentive is any external object or event that motivates behavior. Whereas drive theory bases motivation on internal states, incentive theory emphasizes external stimuli.

Optimal arousal theory hypothesizes that everyone has a physiological need for stimulation and that we constantly strive to maintain an optimal or ideal level of arousal by seeking or avoiding stimulation from the environment. Functioning at an optimal level of arousal maximizes your behavioral efficiency or performance on a variety of tasks. This inverted-U function (the relationship between arousal and performance) was first studied by R. M. Yerkes and J. D. Dodson and is called the Yerkes-Dodson law.

Abraham Maslow theorized that some motivational forces are distinctly human and that human behavior is motivated by a number of competing needs that can be arranged in a hierarchy. The need hierarchy is a systematic listing of needs in priority order, such that the needs farther up the hierarchy can be met only after more basic needs have been satisfied. At the lowest level of the hierarchy are physiological needs, such as hunger and thirst. The very highest need is the need for self-actualization, each individual's need to fulfill his or her potential. Maslow's theory has been very influential both in practical applications and in generating research. Cognitive theories of motivation emphasize the role of thought processes in initiating, maintaining, and guiding behavior. Motivation can come from outside or inside the person. External motivation comes from the outside and takes the form of rewards. Intrinsic motivation comes from within you and causes you to engage in behaviors for no apparent reward. From an evolutionary perspective, motives are seen as mechanisms that have evolved to ensure the survival and reproduction of the species. Both physiological and social motive systems represent adaptations that solved specific environmental problems over the course of evolutionary history. The second section ("Hunger Motivation") focuses on hunger as a form of motivation, beginning with the roles of the stomach and the hypothalamus. Recent studies have confirmed early theories that the stomach has a role in hunger. Receptors in the stomach and upper intestine let us know when we are hungry, help determine our appetites for specific foods, and influence the size of the meal we consume. However, even without a stomach, people will still feel hungry.

Three areas of the hypothalamus associated with hunger are discussed: the lateral hypothalamus (LH); the ventromedial hypothalamus (VMH); and the paraventricular nucleus (PVN). The glucostatic theory suggests that specialized hypothalamic neurons function as glucostats and monitor blood glucose. Others have suggested that the hypothalamus might monitor lipids (fats) in the blood rather than glucose. The set point theory proposes the lipostatic hypothesis. A set point is a biologically based weight at which your body tends to remain. Taste is a powerful determinant of what and how much we eat. Taste preference is both innate and learned and has adaptive functions that provide essential nutrients.

Research has shown that the tendency to become obese is inherited and that people with this genetic tendency store fat more efficiently and consume more food. In addition, heredity might affect metabolic rate, fat cells, a weight set point, and the hypothalamus. However, you cannot gain weight by eating alone. People are affected by external cues, emotional arousal, bad eating habits, and dietary restraints. Reasons for the difficulties experienced by overweight people in their attempts to lose weight and maintain weight loss are explored. This section concludes with a brief discussion of the eating disorders anorexia nervosa and bulimia nervosa.

The third section ("Sexual Motivation") explains that sex, like hunger, is a physiological drive that is necessary for the survival of the species. This section begins with a discussion of evolved differences in sexual behavior in men and women. Sexual arousal is described as a complex process that occurs in a fairly consistent, cyclical pattern. The human sexual response proceeds through four stages. Sexual arousal is also described as a product of biology modified by environment. Neurological and hormonal influences are described. Sexual behavior is also a product of psychological processes and is influenced by learning and the physical attractiveness of a partner. Homosexuality (which has been found in every society since the beginning of recorded history) involves the preference for same-gender sexual partners. Public and professional attitudes toward homosexuality, and the causes of homosexuality, are discussed, and both biological and psychological explanations of homosexuality are explored. This section concludes with a discussion of sexual dysfunction and its treatment.

The fourth section ("Achievement and Social Motivations") considers motives that involve complex cognitive and social elements that appear to be basic to their operation as motivational systems. These clearly human motives include achievement motivation and the needs for affiliation and power. Achievement motivation, a uniquely human drive, is defined as a striving to overcome challenges, improve oneself, attain excellence, and accomplish more than others. This motive is learned and is measured by the Thematic Apperception Test (TAT). This motive also involves the tendencies to achieve success and to avoid failure. Building on this concept, the dynamics-of-action theory hypothesizes that the individual is constantly in a state of activity, rather than a state of equilibrium or rest. Expectancy-value theory focuses on the interplay of the motives to achieve success and avoid failure as they interact with the expectancy of success or failure and the incentive value of the goal to be achieved. Research on achievement motivation has focused on sex differences, the development of achievement motivation, and minority group differences.

Social motives are those that are experienced and satisfied through interaction with other people. The affiliation motive, nearly universal among humans, is a need to associate and interact with other people. The need for power is the need to control or influence the behavior of others. Theory and research on the needs for affiliation and power are described. The fifth and final section ("The Neurophysiology of Motivation") explains that because little is known about the multitude of neurophysiological factors involved in all the various drives, the discussion in this section is limited to two brain centers that play key roles in motivation: the hypothalamus and the reticular activating system. In addition to its important role in regulating hunger and sex, the hypothalamus is involved in thermoregulation (control of body temperature), thirst, and sleep. Although it plays a significant role, the hypothalamus does not function as a unit in controlling drive states. Mechanisms elsewhere in the brain, such as the reticular activating system (RAS), play key roles. The RAS is a neural center for the coordination of activation or arousal arising from various sources, including sensory input and the cerebral cortex. Research with electrical stimulation has indicated that there may be brain "reward centers" that motivate some behaviors.



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