Drives, Biology of

The mechanistic approach to motivation in the 20th century has produced three major drive theories, each stressing that internal tension motivates behavior, and reducing tension reinforces behavior. Freud’s psychoanalytic theory is one such, the ethologists’ theory of instinctive behavior another, and the experimental psychologists’ drive theory is the third. Instincts and drives were thought to be very similar to each other. Both were considered to be biologically important and to motivate behavior. The main advantage of drives were that they were thought to be tangible—to have an easily accessible physiological basis. Instincts were of course assumed to have a physiological basis too, but it was thought hard to get at, bound up heavily in genetic mechanisms. Historically, ethologists stressed the unlearned, and psychologists the learned determinants of behavior.