Reorganization of Equivalence Classes After Reversal of Baseline Relations

Abstract

reversed baseline conditional discriminations after the emergence of equivalence classes. College students' performance was consistent with the reversed baselines in subsequent symmetry tests, but was consistent with pre reversal baselines in transitivity tests. The present study replicated systematically Pilgrim and Galizio's experiment. Following the emergence of two four-members equivalence classes, 9 college students were exposed to reversal of a baseline conditional discrimination, training of a new conditional discrimination , reversal of another baseline conditional discrimination, and return to the original baseline. Both symmetry and transitivity performances were consistent with the reversed baselines for most participants. These results may be due to increased strength of the reversed baselines, trained with continuous reinforcement and reviewed before probes, whereas Pilgrim and Galizio trained reversals with intermittent reinforcement in the context of probing. The use of different stimuli and stimulus display may have also affected the results.When humans learn conditional relations through a matching-tosample procedure, they often show also emergent relations. Thus, if participants learn a relation AB (selecting comparison stimuli B1, B2, .. . , Bn, conditionally upon samples A 1, A2 , ... or An , respectively), this relation is usually shown to have the property of symmetry: The relation

Reorganization of Equivalence Classes: Evidence for Contextual Control by Baseline Reviews Before Probes

“…Participants of the present study nearly always reversed performance in symmetry probes consistently with the most recent baseline but, differently from that in the study of Garotti et al (2000), performance in transitivity probes was variable and often was not consistent with class reorganization. Galizio (1990, 1995) also found this dissociation between outcomes in symmetry and transitivity tests after reversal of baseline conditional discriminations.…”

“…The results of Garotti et al (2000) support the hypothesis that performance on postreversal probes depends on conflicting reinforcement histories, so that the prevailing history may depend on procedural details that strengthen one relative to the other . .…”

“…The procedure of Experiment 2 replicated that of Garotti et al (2000), adding a third comparison stimulus in conditional discriminations. Results of Experiment 2 were similar to that study.…”

“…It is possible, therefore, that the training conditions in the study of Pilgrim and Galizio strengthened the original baseline relative to the reversal, so that the original baseline prevailed over the reversed one when both could serve as the basis for selection in equivalence probes. Garotti, de Souza, de Rose, Molina, and Gil (2000) replicated the general design of the study of , but made reversal training more comparable to the training of the original basel. ine.…”

“…To investigate this possibility, the present study conducted two experiments: The first omitted baseline reviews and the second included them. The design of training and probes in this study was similar to that of Garotti et al (2000), however, the number of comparison stimuli in conditional discrimination trials was increased to three in order to minimize the possibility of control by relations between sample and S-, in an attempt to further reduce the variability of probe performance.…”