ABSTRACT
In chapter 1, we noted that behavior analysts use the term environment to refer to events and stimuli that change behavior. These events may be external to the organism or may arise from internal physiology. The sound of a jet aircraft passing closely overhead and that of an upset stomach may both be classified as aversive by their common effects on behavior. That is, both events strengthen any behavior that removes them. In the case of a passing jet, people may cover their ears; a stomachache may be removed by taking antacid medication.
