Measures of temporal discrimination in fixed-interval performance: A case study in archiving data

Many experiments on animal learning and performance consist of discrete events, such as the onset or termination of a stimulus, the delivery of food, or a response that closes or opens a switch or that breaks a photobeam. Investigators of operant conditioning have made extensive use of the cumulative recorder to record the primary data that consist of times of occurrences of these discrete events (Ferster & Skinner, 1957). These records, although extensive, are not in a convenient form for subsequent analysis. In most cases, only selected examples of performance could be presented. To reduce the random error on individual trials of individual animals, most investigators have presented summary measures of behavior averaged across many trials, and sometimes across many animals. Although the primary data can produce all of the summary measures, the summary measures cannot be used to reconstruct all other summary measures. A good quantitative theory of the processes involved in animal learning and performance should lead to the prediction of the primary data (and thus, all summary measures), not just selected summary measures. The value of archiving primary data will be developed with a case study of an experiment with fixed-interval schedules of reinforcement. In a fixed-interval schedule of reinforcement, a pigeon, a rat, a human, or some other animal receives a reinforcer following a response after a fixed interval following some event, such as food delivery or stimulus onset. Fixed-interval schedules of reinforcement have been used extensively for many years to investigate the ability of animals to adjust to the temporal regularities of their environment.