Motivating Operations in Drug-Discrimination

Motivating operations (MO) play an important role in learning and performance. According to the behavior analytic conceptualization, MOs alter the probability of responses that lead to relevant reinforcers and alter the reinforcing " value " of those reinforcers (e. that one way in which MOs influence stimulus control is by influencing the control of behavior by discriminative stimuli. Interestingly, in studies with nonhumans, such an effect is commonly observed when lights and tones are used as discriminative stimuli, but not when drugs are used. Procedural differences across studies involving the species studied, the measurement system used to quantify performance, and the manner in which MOs were manipulated, may account for the discordant results. The present research evaluated this possibility in a series of three experiments. Results of these experiments suggest that the discrepant results obtained in previous studies were not due to the measurement system, testing procedure, or the species used. The manner in which MOs are manipulated may, however, play a role, and it appears that such variables affect stimulus control only when motivation is increased relative to the baseline condition. ! ii! ACKNOWLEDGMENTS I would like to thank my advisor Dr. Alan Poling for his guidance and support. I would also like to thank my dissertation committee members, Dr. Thanks to my lab-mates for making the research environment the most pleasant place. Last but not least, I would like to thank my family, girlfriend, and the dogs for their love and support all along.