ABSTRACT
Responses can not only produce stimuli to which others react, but can also produce stimuli to which the subject himself reacts. These stimuli function in exactly the same way as other stimuli; if they are strong, they have drive value; if they are distinctive, they have cue value. There is reason to believe that the drive value of self-induced stimuli is the basis of acquired drives, acquired rewards, and purposes, and that the cue value of these stimuli is the basis of foresight and reasoning. Language, which plays such an enormously important rôle in human behaviour, is an elaborate system of responses producing stimuli which act as cues.
