Murray Sidman's contributions to clinical behavior analysis

Murray Sidman was not himself a clinician nor directly involved in clinical research. Nevertheless, his experimental and conceptual work, especially in the area of stimulus equivalence, profoundly influenced the development of clinical behavior analysis. Before his work on stimulus equivalence, clinicians with a behavior analytic world view working with verbally sophisticated humans, were making some progress in understanding clinical phenomena and in developing innovative therapies. However, given the obvious and predominant role of verbal processes in both the development and treatment of clinical problems, that progress was constrained by the existing behavior analytic account of verbal behavior. Most fundamentally, it was hard to understand how, in the apparent absence of direct training, verbal events, even novel verbal events, acquire the functions of the nonverbal events that they stand for or represent. Sidman's work on stimulus equivalence, especially the transfer (transformation) of functions, offered an answer and thereby provided a conceptual framework of symbolic behavior around which clinical behavior analysis could cohere and develop.