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Summary: Biological Motives

Biological motives include hunger, thirst, the pursuit of pleasure, and the avoid­ance of pain. An early attempt to specify how these motives affect animal behavior was the ambitious theory of Clark Hull.

Hull borrowed from the concept of homeostasis or biological regulation. His assumption was that biological motives followed the pattern of homeostasis. After Hull, this conceptual linkage is still reflected in concepts such as the set-point for fat regulation.

Modern theories of hunger involve multiple factors. For example, obesity is strongly influenced by genetics, but palatability of food plays a role, and even habitual fidgeting (small nervous move­ments) can influence fat deposition over time.

Pleasure and pain are regulated by a hedonic control system. Solomon's opponent process theory explains hedonic rebound: the phenomenon where a period of happy or sad emotion is followed by its opposite.

The neurotransmitter dopamine is involved in neural pathways to the prefrontal cortex of humans, a key area for pursuing goals. Dopaminergic pathways energize behaviors aimed at reinforcements.

Research has shown dopamine levels are elevated by anticipation of reinforcing events. This applies to addictive drugs but also a wide range of normal and desirable behaviors. Dopamine levels seem to increase whenever people look forward to something they enjoy.

The concept of stress-induced behavior resembles Hull's original drive concept. It also resembles popular ideas about motivation held by non-scientists: motivation involves pep or energy, generated in response to environmental challenge (stress), and shaped or directed by situational factors.

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