Concurrent performances: rate and accuracy of free-operant oddity responding

In pigeon's oddity performances, maintained by variable-interval reinforcement of pecks on the odd key of three keys in a triangular array, accuracy and response rate varied inversely with the rate of variable-interval reinforcement scheduled concurrently for pecks on a fourth, spatially isolated key. But when variable-interval and extinction components alternated in a multiple schedule for pecks on the spatially isolated key, oddity accuracy was greater during variable-interval components than during extinction components. Oddity response rate was not affected systematically by the alternating components. Changeovers between the oddity keys and the spatially isolated key were frequent during variable-interval components; responding occurred almost exclusively on the oddity keys during extinction components. This difference in performance during the two components was eliminated by arranging stimulus-correlated variable-interval reinforcement in the multiple schedule on the spatially isolated key: a stimulus was presented in the variable-interval components only when reinforcement became available, thereby reducing responding on this key to near-zero levels in both components while maintaining the variable-interval reinforcement. The effect of the multiple-schedule components on oddity accuracy was not altered, however, and thus apparently depended directly on concurrent reinforcement and not on differential sequential properties of concurrent responding during the two components.