ABSTRACT
The importance of motivation in both normal and abnormal behavior is generally recognized. This chapter describes experiments from laboratory in which a combination of behavioral, physiological, and pharmacological techniques is used to study motivation. The experiments deal with hunger, thirst, sex, aggression, and a centrally aroused pain-fear-like response. These drives are induced or reduced in a variety of unusual ways, such as by direct electrical or chemical stimulation of the brain. Most studies of hunger have used but a single technique, measuring the amount of food consumed. If food injected directly into the stomach produces a prompt reduction in the strength of hunger, the drive-reduction hypothesis of reinforcement demands that such injection should serve as a reward to produce learning. But since food taken normally by mouth produces a greater reduction, it should serve as a stronger reward.
