Sidman’s Contingency Analysis of Stimulus Equivalence: The Role of Biology and Learning History

Several competing theories on the origins of stimulus equivalence is found in the literature. Murray Sidman proposes that it seems likely that stimulus equivalence is a direct outcome of the n-term operant contingency, in the same way as reinforcement or discrimination. In contrast to other theories on equivalence, Sidman suggests that stimulus equivalence performance cannot be explained by other behavior principles, but is instead is a behavioral primitive and the product of biological evolution. In addition, he suggests that stimulus equivalence as seen in the laboratory is not the outcome of a learning history making derived relational responding possible, but rather is the result of a learning history allowing for the contextual breakdown of stimulus equivalence. This notion of inborn unity and learned differentiation is not uncommon in psychological theories on child development, and figures prominently in theories by Jean Piaget and William James, among others. The current paper will explore the experimental and conceptual background for Sidman’s theory on the evolutionary origins of stimulus equivalence and discuss arguments for the adaptive significance of stimulus equivalence.