Control of response duration by delayed reinforcers: A systematic replication.

Three rats responded under schedules of delayed reinforcement in which sweetened condensed milk delivery depended upon lever-press durations exceeding or falling under a programmed value. For all rats, response durations increased compared to those emitted under a fixed-ratio 1 schedule when unsignaled delayed reinforcers were programmed for lever-press durations exceeding 1 s. For two of the rats, response durations also decreased when delayed reinforcer delivery was programmed for durations less than 1 s. Extinction reduced response rate, but did not affect response duration. Data suggest that the rate decreasing effects of unsignaled delayed reinforcers may be separated from the effects those reinforcers have on a targeted continuous dimension.