From direct contingencies to derived relations: the ever-developing nature of theory and practice in behavior analysis.

Purpose: To illustrate the processes of development within the behavioral theory and the corresponding expansion of the areas in which it is applied, especially the advancement (conceptual developments) of the functional analysis of language inspired by Relational Frame Theory (RFT) research. Views: Classical and operant conditioning are well-established behavioral learning processes, discovered and described at the beginning of the twentieth century. They provide the tools for analyzing, establishing and modifying the functions of stimuli and responses of the organisms through manipulation of the environment. Although B. F. Skinner provided grounds for the functional analysis of complex behaviors such as language, it was not until the beginning of the twenty-first century that RFT was introduced. From this moment behavior analysts could use behavioral principles to explain how stimulus functions may change without direct learning. The practical application of the growing knowledge about Arbitrarily Applicable Relational Responding (AARR), a basic generalized operant described within RFT, allows us to analyze, explain and change behaviors that had hitherto been beyond the scope of behavioral therapy. The continued growth and development of behavior theory and practice holds the promise for an expansion of its application to new areas and populations in need. One such development is the functional analysis of verbal behavior e.g., relational frames, ROE (relating-orienting-evoking). Conclusions: It seems useful to add advancements proposed by RFT to the behavioral toolbox with which we could effectively describe, explain and change behavior with precision, scope and depth.