MEP - Specific Topics in Motivation Lesson

Learning Target:

  • Discuss the biological underpinnings of motivation, including needs, drives, and homeostasis. 

AP psychology course and exam description, effective fall 2020. (n.d.). https://apcentral.collegeboard.org/media/pdf/ap-psychology-course-and-exam-description.pdf

Underpinnings of Motivation          Get Moving.png

Motivation is rooted in the concept of needs, which are the basic physiological and psychological requirements that individuals must meet to survive and thrive. Drives are internal states of tension that motivate individuals to engage in behaviors that will reduce the tension and fulfill their needs.

Homeostasis is another key concept in motivation. By maintaining a stable internal environment, the body maintains temperature, pH balance, and fluid balance. To achieve homeostasis, individuals engage in behaviors that satisfy their needs and reduce their drives.

The hypothalamus is a crucial structure in the brain that plays a key role in motivation regulation. Several physiological processes are controlled by this organ, including hunger, thirst, and body temperature. The brain's reward system, which releases dopamine in response to pleasurable experiences, also plays a key role in motivation. Dopamine is released when people engage in behavior that fulfills their needs, reinforcing the behavior and creating a sense of reward.

Biological Basis of Hunger

Most of us are under the impression that when our stomachs are full, we do not feel hungry, and when they are empty, we receive signals to eat. Researcher Al Washburn conducted a study in which he had participants swallow balloons and then inflated them simulating a full stomach. What he found was that even with a "full" stomach after a few hours, participants reported feeling hungry again. The results showed us that hunger does not just come from our stomach, it comes from a brain structure called the hypothalamus.

Image showing the Lateral hypothalamus (hunger center) and Ventromedial hypothalamus (satiety center) in the brain, as well as a rat with Lateral hypothalamus lesions (anorexia), a normal rat, and a rat with Ventromedial hypothalamus lesions (obesity)

Image of large mouse and a small mouse. There are two areas of the hypothalamus that play a role in controlling hunger. First, there is the lateral hypothalamus which, if stimulated, brings on hunger. When you feel hunger pangs your lateral hypothalamus is being stimulated. If this structure is lesioned, you will never feel hungry again. Then there is the ventromedial hypothalamus which when stimulated signals a feeling of satiation. If this structure is lesioned, you will never feel full again.

With a normally functioning hypothalamus, the two work together to cue us to begin and stop eating at the appropriate times. This energy balance is the essence of a theory called the set point theory. Our set point is the natural optimal weight at which our bodies strive to maintain. It is defended by regulating feelings of hunger and our body's metabolism. While our body weight tends to stay stable over time it does not mean that our baseline body weight is fixed. For most, as we age there is a strong tendency to drift to heavier average body weight.

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