Changing the Meaningfulness of Abstract Stimuli by the Reorganization of Equivalence Classes: Effects of Delayed Matching

Abstract

Previous research has shown that arbitrary stimuli acquire the valence of facial expressions that convey different emotions when both become members of the same equivalence class. The present study investigated whether stimuli that shifted class membership and became equivalent to another facial expression would change in valence accordingly. Fifty-four college students formed equivalence classes A1B1C1D1, A2B2C2D2, and A3B3C3D3, where A1, A2, and A3 were facial expressions of happiness, neutrality, and anger, respectively. Semantic differential ratings showed that D1, D2, and D3 acquired the valences of the equivalent facial expressions. Training for class reorganization was then conducted, altering the CD relation, so that D2, D3, and D1 would become equivalent to expressions of happiness, neutrality, and anger, respectively. This training was conducted in a delayed matching-to-sample format for one group of participants and in a simultaneous matching-to-sample format for another group. When asked to rate the D stimuli again, participants who showed class reorganization showed valence changes according to the facial expression to which these stimuli became equivalent after training of the altered CD relation. Valence changed more for participants trained for class reorganization with delayed matching. Participants who did not pass the test for class reorganization did not show changes in the valence of the D stimuli. These results indicate that training parameters affect the extent to which stimuli change in meaning when they shift membership in equivalence classes.