LAUSR

ABSTRACT The establishment of sample/S+ (select) or sample/S− (reject) controlling relations affects equivalence-class formation. The present experiment aimed to evaluate transitivity and equivalence test results when, during training, some of the baseline relations among stimuli presented during tests were established under reject control and others were established under select control. Five participants had learned in a previous study to respond to conditional discriminations AB, BC, and CD under reject control and to DE and EF relations under select control. In the present investigation, such baseline-trained relations were reviewed and, after that, (1) one-node CE-transitivity and EC-equivalence tests, (2) two-node BE-transitivity and two-node EB-equivalence tests, and (3) four-node AF-transitivity and four-node FA-equivalence tests were carried out. Results suggest that during transitivity and equivalence tests involving one stimulus set related under reject and another under select control (CE and EC tests), participants scored high. Increasing the number of nodes involved during tests, however, resulted in variability. The possibility that the commonly observed failures of equivalence class formation may be the result of heterogeneous controlling relations among the stimuli comprising the set or putative equivalence class is discussed.