The inborn tendency of every member of a certain species to behave in the same way given the same situation or set of stimuli.

Behavior is considered instinctive only if it occurs in the same form in all members of a species. Instincts must be unlearned and characteristic of a specific species. Animals provide the best examples of instinctive behavior. Members of a certain bird species may naturally build nests, feed and protect their young, and migrate in the exact same ways without being taught. Other animals, such as gray squirrels or dogs, behave in manners characteristic of gray squirrels or dogs, respectively, even when raised apart from other members of their species. Ethologists (scientists who study animals in their natural environments) devote much of their efforts to the observation of instinctive behavior.

Throughout history, theorists have speculated on the role of instinct in determining human behavior. While the hypothesis that animal behavior is governed largely by innate, unconscious tendencies has been widely accepted, the presence and power of instincts in humans have been a source of controversy. Early Christian theorists believed that only animals were guided by instincts, asserting that the absence of instinct-governed behavior and the presence of a moral code provided the major distinction between humans and animals.

Instinct assumed a more prominent place in behavior theory in later years. In the late 1800s, American psychologist and philosopher William James (1842–1910) proposed that human behavior is determined largely by instinct, and that people have even more instinctual urges than less complex animals. James believed that humans share certain biological instincts with animals, and that human social instincts like sympathy, love, and modesty also provide powerful behavioral forces.


Drive theory—
Put forth by famed neurologist Sigmund Freud, this theory postulates that human behavior is motivated by the desire to reduce the tension caused by unfulfilled instinctive urges or drives.
One who studies animal behavior in the animal's natural habitat.

Austrian neurologist Sigmund Freud (1856–1939) considered instincts to be basic building blocks of human behavior and to play a central role in his drive theory, which postulates that human behavior is motivated by the desire to reduce the tension caused by unfulfilled instinctive urges or drives. For instance, people eat when they are hungry because unsatisfied hunger causes tension, and eating reduces that tension. For Freud, the life instinct (which he identified as Eros) and its components motivate people to stay alive and reproduce. The death instinct (Thanatos) represents the negative forces of nature. Another theorist, English psychologist William McDougall (1871–1938), helped to develop the instinct theory of motivation, noting that instinctive behavior is composed of perception, behavior, and emotion, and named 18 different instincts. He described instincts simply as “inherited dispositions.”

It is useful to note a nonscientific use of the term instinct. In casual conversation, a person may use instinct to mean “natural” or “automatic” in describing a baseball player's instinct for batting, for example. This use of the term would not meet the scientist's criteria for instinct.

The debate continues today over the role of instinct in human behavior, as the balance between learned behavior and innate urges remains a subject ripe for continued research and discussion.



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