DISCRIMINABILITY OF FREQUENCY OF FOOD OR STIMULUS PRESENTATIONS IN VARIABLE‐TIME SCHEDULES

Abstract

Pigeons responded in a two‐alternative forced‐choice task in which reinforcement was dependent upon the frequency of events that occurred in an immediately preceding schedule sample. On a given trial the events were either brief food presentations or brief visual and auditory stimulus changes. High levels of stimulus control were obtained by food‐presentation schedules only. Discriminative control by frequency or stimulus change was absent. Stimulus control by food frequency was decreased by the imposition of a delay period between the schedule sample and the choice. Moreover, stimulus control by food frequency was related to the ratio of food‐presentation schedule pairs when novel schedules were presented in a transfer test.