Abstract
Three theories have been proposed in behavior analysis to explain the establishment of stimulus equivalence. Sidman's (1994) equivalence relation theory suggests that stimulus equivalence is a fundamental behavioral function caused by reinforcement contingencies, and asserts that learning is unnecessary for its establishment. In contrast, the relational frame theory (RFT) suggests that stimulus equivalence results from previous learning regarding many different stimulus-relationships. On the other hand, the naming theory focuses on the naming process, or the circular relationship between the behaviors of the speaker-listener. The latter two theories hold that verbal learning is necessary for the formation of stimulus equivalence. Moreover, naming theory suggests that equivalence relations are formed by verbal responses, whereas the other two theories suggest that naming is the same behavioral process as equivalence. In conclusion it is suggested that analysis of stimulus function is crucial to understand cognition and language.
