Date of Award


Degree Name

Master of Arts



First Advisor

Dr. Jack L. Michael

Second Advisor

Dr. Kay Malott

Third Advisor

Dr. Alan Poling

Access Setting

Masters Thesis-Open Access


Previous studies using concurrent variable-interval variable interval schedules have suggested that molar, not molecular variables primarily control choice responding. These studies examined pigeons performance under discrete-trial concurrent mixed fixed-ratio fixed-ratio schedules of reinforcement. When each alternative provided two reinforcements per 100 responses, pigeons preferred the alternative containing the shorter initial fixed-ratio. Subsequent studies attempted to shift preference through manipulations of ratio requirement and reinforcement duration in either alternative. Preference was shifted from the mixed fixed-ratio fixed-ratio only when the reinforcement associated with the first component was eliminated. Under all other conditions, pigeons preferred the mixed fixed-ratio fixed-ratio schedules with the shorter initial component even when, overall, that schedule yielded briefer access to food or required more behavior to obtain equivalent access. These results indicated that molar response/reinforcer relations exercise little control over choice responding under the conditions of the reported studies.