Failure to observe untested derived stimulus relations in extinction: implications for understanding stimulus-equivalence formation

Wilson and Hayes (1996) and Doughty, Kastner, and Bismark (2011) observed resurgence of past equivalence relations when newer equivalence relations were punished or extinguished, respectively. Their findings support the notion that deriving stimulus relations is a form of operant behavior. Although there is consensus regarding the operant nature of deriving untrained stimulus relations, the necessary and sufficient conditions that establish these relations remain unclear. For example, in the aforementioned work, the resurgent equivalence relations were tested earlier in each study. The present research investigated whether this resurgence of equivalence relations requires their initial testing. In Experiment 1, college students received arbitrary matching-to-sample training in Phase 1. After these baseline discriminations were established, equivalence testing was omitted. In Phase 2, four 4-member equivalence classes were established that were inconsistent with the Phase-1 training. These Phase-2 relations then were extinguished to test whether the equivalence relations consistent with Phase-1 training would occur. Unlike in earlier research, these untested relations did not occur reliably. This finding was replicated in Experiment 2, and additional tests of stimulus relatedness did not reveal any evidence of derived stimulus relations consistent with the Phase-1 training. The present research extends other findings suggesting that the equivalence-testing context helps establish these stimulus classes.