ALTERNATIVE FIXED-RATIO FIXED-INTERVAL SCHEDULES OF REINFORCEMENT

Five rats were trained under alternative fixed‐ratio fixed‐interval schedules, in which food reinforcement was provided for the completion of either a fixed‐ratio or a fixed‐interval requirement, whichever was met first. Overall response rate and running rate (the rate of responding after the postreinforcement pause) decreased for all subjects as the fixed‐ratio value increased. As the proportion of reinforcements obtained from the fixed‐ratio component increased and the alternative schedule approached a simple fixed ratio, overall response rate and running rate both increased; conversely, as the proportion of reinforcements obtained from the fixed‐interval component increased and the alternative schedule approached a simple fixed interval, response rates decreased. Postreinforcement pause length increased linearly as the average time between reinforcements increased, regardless of the schedule parameters. A break‐run pattern of responding was predominant at low‐and medium‐valued fixed ratios. All subjects displayed at least occasional positively accelerated responding within interreinforcement intervals at higher fixed‐ratio values.