Schedules of Reinforcement

The book's central claim is that the temporal patterning of reinforcement—the rule determining when responses produce consequences—is a fundamental determinant of behavior in its own right. Ferster and Skinner demonstrate that each schedule generates a characteristic, reproducible response pattern: fixed-ratio schedules produce high steady rates with post-reinforcement pauses, fixed-interval schedules produce scalloped patterns of acceleration, and variable schedules produce steady rates. These patterns are orderly enough to serve as baselines against which other variables—motivation, drugs, stimulus control—can be measured. The book thus establishes that behavior is not merely strengthened or weakened by reinforcement but is shaped into specific temporal forms by the contingencies governing reinforcement delivery.

The cumulative recorder is an instrument that draws a continuous line, stepping upward with each response and moving horizontally with time. Reinforcements are marked by brief diagonal deflections of the pen. The resulting cumulative record displays the rate and patterning of behavior in a single visual trace, making schedule effects immediately visible. Ferster and Skinner rely on it because it captures the temporal structure of behavior—the pauses, accelerations, and steady states—that summary statistics would obscure. The book contains hundreds of cumulative records, and its arguments are conducted through the visual comparison of these traces. The recorder became the signature instrument of the experimental analysis of behavior, and the book is its most comprehensive demonstration.

Schedules of Reinforcement extends the program announced in The Behavior of Organisms (1938). The earlier book introduced the operant, established rate of responding as the basic datum, and described elementary schedules. The 1957 volume, co-authored with Charles Ferster, systematically explores the schedule parameter space across hundreds of experiments. It transforms schedules from a methodological detail into a central theoretical topic. Where The Behavior of Organisms was programmatic and relatively brief, Schedules of Reinforcement is encyclopedic—its 739 pages present an exhaustive empirical mapping. Skinner regarded it as one of his most important technical contributions, and it remains the definitive reference for schedule effects.

Charles B. Ferster (1927–1981) was a behavioral psychologist who worked with Skinner at Harvard and later became a leading figure in the experimental analysis of behavior. He conducted much of the experimental work reported in Schedules of Reinforcement, running the pigeons and rats, maintaining the cumulative records, and organizing the vast data set. Ferster later applied behavioral principles to clinical populations, co-authoring Psychotherapy by Reciprocal Inhibition with Joseph Wolpe. The collaboration with Skinner was hierarchical—Skinner provided the theoretical framework and the book's conceptual organization, while Ferster supplied the sustained experimental labor. The book's acknowledgments make clear that Ferster was responsible for the bulk of the data collection.

The book was recognized immediately as a landmark empirical contribution. Reviewers praised the clarity of the cumulative records and the systematic coverage of schedule parameters. However, some critics noted that the book was primarily descriptive rather than theoretical—it catalogued schedule effects without providing a quantitative model to predict them. This criticism became more prominent as mathematical models of reinforcement (such as matching theory and molar accounts) developed in the 1960s and 1970s. The book's atheoretical stance was deliberate: Skinner believed that premature theorizing would impede the accumulation of orderly data. Later commentators have observed that the book's descriptive richness remains unmatched, even as its theoretical reticence became a target for subsequent researchers.

Schedule research has had wide practical influence. In applied behavior analysis, schedules are used to design interventions for developmental disabilities, classroom management, and organizational behavior. In behavioral pharmacology, schedule-controlled responding is a standard assay for assessing drug effects on behavior. In behavioral economics, schedules model choice and preference. Token economies use ratio and interval schedules to maintain appropriate behavior in institutional settings. The concept of intermittent reinforcement explains why gambling and other forms of pathological behavior persist despite inconsistent payoffs. These applications all trace back to the systematic mapping of schedule effects presented in Ferster and Skinner's volume, which established the empirical foundation for treating reinforcement schedules as a fundamental independent variable.