Final answer:
An organism's behavior is driven by the need to maintain homeostasis, which is the stable state of internal conditions regulated by physiological processes. The drive theory of motivation highlights how deviations from homeostasis create needs that drive behavior aimed at reestablishing equilibrium.
Step-by-step explanation:
Psychologists believe that an organism's behavior is motivated by the need to achieve a state of balance in which the body functions effectively. This state is known as homeostasis. Homeostasis refers to the process by which an organism maintains a stable internal environment despite external changes. The body achieves this through a series of adjustments to keep physiological variables within a certain range. For instance, the regulation of blood sugar levels after eating reflects the body's attempt to maintain homeostasis: if blood sugar is high, the body works to lower it, and vice versa.
The drive theory of motivation posits that deviations from homeostasis create physiological needs, leading to psychological drive states that compel an organism to act to restore balance. A common example is the need to eat when hungry to restore blood sugar levels to normal, thereby bringing the system back to homeostasis. This concept is critical to understanding a variety of behaviors that aim to keep an organism's internal state regulated within a survival-friendly range.