Changeover contingencies and choice on concurrent schedules

Abstract

Pigeons were trained on a multiple concurrent schedule with two components per session. In one component, changing schedules required the completion of a small fixed ratio on the switching key (a fixed-ratio changeover, or FRCO), and in the other component, changing schedules required only one switching response but engaged a changeover delay (COD) during which keypecks were not reinforced. Response ratios overmatched reinforcer ratios under the FRCO but undermatched under the COD. There was no difference in time allocation. In addition to these molar regularities in behavior, there were characteristic differences in performance at the molecular level. These local patterns of behavior, which can be explained within the context of contingencies created by the different changeover requirements, appear to underlie differences in performance at the molar level. Obtained molar differences in performance are not compatible with the assumption that there is a "general outcome" on concurrent schedules; and explaining these molar differences in performance in terms of the local contingencies of reinforcement is contrary to the assumption that behavior is allocated as a function of molar distributions of reinforcers. © 1993 Psychonomic Society, Inc.