3RD-ORDER EQUIVALENCE CLASSES

Two experiments were conducted to examine the emergence of third-order equivalence classes. In Experiment 1, college students were trained i n three successive phases to perform first-, second-, and third-order baseline conditional discriminations. In each phase, after attaining t he baseline criterion, equivalence tests were conducted. Passing a tes t in a given phase was required for advancing to the next phase. Five of ten subjects showed performances consistent with third-order equiva lence classes. To understand why higher-order relations sometimes did not emerge, the study was replicated. In Experiment 2, four subjects w ere instructed to talk aloud during all training and test phases. Two subjects showed third-order equivalence; the other two failed the seco nd-order symmetry test and were unable to advance beyond Phase 2. A pr otocol analysis (Ericsson & Simon, 1980; Wulfert, Dougher, & Greenway, 1991) of their verbal responses revealed that their behavior was not controlled by the intended second-order conditional stimuli. When cont rol by these stimuli was established through instructions, second-orde r, and in Phase 3 third-order, equivalence relations emerged. This res earch replicates previous studies on second-order equivalence and exte nds contextual control over emergent relations to the third order. The demonstration of complex emergent relations may have implications for a behavioral analysis of cognitive-verbal phenomena such as concept f ormation and classification.