Interdependence of equivalence relations during the formation of an equivalence class: Punishing relational responding through a default-response option

This study investigated the effects of punishing equivalence responding within a single class of stimuli. Across two experiments, 25 participants completed equivalence training via a match-to-sample task including a default-response option (none of them is correct). In Phase 1 for both experiments, relations A1→B1, A2→B2, C1→B1, C2→B2 were trained and then tested for equivalence emergence (Test 1). In Phase 2, equivalence responding of Class 2 (A2→C2, C2→A2) was explicitly punished, with the default-response option instead appearing as the correct target stimulus. The default option was presented more frequently in Experiment 2. In Phase 3, relations A1→D1, A2→D2 were trained and a Test 2 was applied to observe the emergence of all potential equivalence relations. Participants in Experiment 1 and Experiment 2 reduced significantly equivalence responding from Test 1 to Test 2 in both classes. These results provide evidence of the interdependence of equivalence relations during the formation of an equivalence class. The punishment of two equivalence relations deteriorated previous equivalence relations and impeded the emergence of potential new relations. Furthermore, the differences observed between Experiment 1 and Experiment 2 indicate that the default option increased the impact of punishment. This option seems more effective than reversal to punish relational responding.