Theories of Motivation for AP Psychology
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Charles Darwin's theory of Natural Selection indicated that individuals best adapted to their environment will be more likely to survive and reproduce, passing their favorable characteristics on to the next generation. As a result, a beneficial trait (one with high adaptive value) tends to become more common in succeeding generations. Eventually almost all individuals in the population will have the beneficial characteristic. Darwin believed that many behaviors were characteristics that could be passed on. William James thought that motivation by instincts was important for human behavior. In the early 1900s, a small group of psychologists led by William McDougall believed all thought and action necessarily resulted from instincts such as curiosity, aggression, and sociability. Sigmund Freud's theory of personality is based on instincts that motivate sex and aggression. Instincts are complex, inherited behavior patterns characteristic of a species. To be considered a true instinct, the behavior must be stereotypical, performed automatically in the same way by all members of a species in response to a specific stimulus. Birds and butterflies flying south to mate, or salmon swimming upstream to mate, are examples of animals carrying out their instincts, also called fixed-action patterns. An example of an instinct was investigated by ethologist and animal behaviorist, Konrad Lorenz, who worked with baby geese. These and other birds form an attachment to the first moving object they see or hear soon after birth by following that object, which is usually their mother. This behavior is known as imprinting. When Lorenz was the first moving object they saw, the baby birds followed him.
Evolutionary psychologists may work in the field of sociobiology, which tries to relate social behaviors to evolutionary biology. For example, they look at evolutionary mating patterns that differ between the two sexes; a male may be motivated to mate with multiple partners to increase the chance of his genes getting into the next generation, while a female might be motivated to mate for life with the male who has the best resources to take care of her and her children.
Psychologists today debate if there are any human behaviors that can be considered true instincts. Is rooting/sucking behavior complex enough to be considered instinctive behavior, or is it merely reflexive? How much of human behavior is instinctive? Psychologists have found it necessary to devise other theories beyond instinct/evolutionary theory to account for human behavior.
Drive Reduction Theory
According to Clark Hull's drive reduction theory, behavior is motivated by the need to reduce drives such as hunger, thirst, or sex. The need is a motivated state caused by a physiological deficit, such as a lack of food or water. This need activates a drive, a state of psychological tension induced by a need, which motivates us to eat or drink, for example. Generally, the greater the need, the stronger the drive. Eating food or drinking water reduces the need by satisfying our hunger or quenching our thirst, and our body returns to its state of homeostasis. Homeostasis is the body's tendency to maintain an internal steady state of metabolism, to stay in balance. Metabolism is the sum total of all chemical processes that occur in our bodies and are necessary to keep us alive. Scientists have identified many of the neural pathways and hormonal interactions associated with biological needs and drives. For example, receptor cells for thirst and hunger are in the hypothalamus. Drive reduction theory accounts well at least to some extent for primary motives such as hunger, thirst, pain, and sex. This biologically based theory does not account as well for secondary motives such as achievement, affiliation, autonomy, curiosity, power, and play that are social in nature.