Historically, a dominant concern of students of learning and conditioning has been investigation of the effects of hedonically valued stimuli on antecedent behavior or on the response-evoking properties of other stimuli predictive of their occurrence. In contrast to this, Solomon and Corbit (1974) have proposed a general theory of acquired motivation, which, in large part, emphasizes the importance of the aftereffects of exposure to hedonically valued stimuli. Briefly, the theory proposes that such exposure induces an affective reaction that will quickly rise to a peak, stabilize, and subsequently return to baseline at or shortly after termination of the stimulus. The onset of this primary affective process, termed the A-process, is held to trigger an opponent reaction of opposite hedonic sign. This aftereffect, or B-process, can be seen in its pure form only following stimulus termination. It is held to have at least five unique properties: (a) a slow rise-time relative to the A-process, (b) a relatively long decay time, (c) a weakening with disuse, (d) strengthening as a function of repeated exposure to the inducing stimulus, and (e) a reinforcement function.