Quantifying Interaction Effects in Operant Relapse: An Introduction to Isobolographic Analysis

In studies of operant relapse, the effects of contingency and context changes are often examined in isolation to clarify their individual contributions to the reoccurrence of a previously extinguished target behavior. In recent years, a section of the relapse literature has examined whether the combination of contingency and context changes interact to produce additive, superadditive, or subadditive effects. Yet, absent from the relapse literature is a formalized quantitative framework for empirically determining the nature of these interactions. Isobolographic analysis is one such framework that has been extensively applied in the pharmacological literature to assess interactions between drug combinations. This article introduces the topic of linear and nonlinear isobolographic analysis and the feasibility of its direct application to the study of operant relapse. Illustrative examples are presented using a hypothetical relapse arrangement, and an alternative analytic method is discussed that may be better suited to behavioral research. This work aims to advance terminological accuracy and methodological precision in relapse research and encourage the integration of quantitative interaction models within operant relapse preparations in which participants undergo mixtures of contingency and context changes during a relapse test.