Duration of keypecks in variable-interval schedules of reinforcement

Abstract

An experiment was conducted to determine the duration of pigeons’ keypecks during three separate variable-interval (VI) schedules of reinforcement. Pigeons were exposed to VI 30-sec, VI 60-sec, and VI 120-sec schedules of reinforcement for 20 sessions each. Response durations were analyzed in terms of VI schedule value, location in time during the interreinforcement interval, and local patterns of short- and long-duration pecks. For three out of four birds, the mean response duration was reliably longer for the VI 30-sec schedule than for the VI 120-sec schedule. Results for the VI 60-sec condition were equivocal. Mean duration of response was constant throughout the VI interval, showing no change over time. No specific pattern of long and short pecks was detected. The results confirm the existence of a range of response durations during VI schedules of reinforcement and suggest that duration of response varies with VI schedule changes.