Emergent conditional discriminations in children and adults: stimulus equivalence derived from simple discriminations.

This study examines whether trained and derived simple discriminations lead to conditional relations between discriminative stimuli of the same and opposite (S+, S-) functions. After being trained on an arbitrary X-Y task (X1-Y1, X2-Y2) and on two simple discrimination tasks (A1+/A2- and B1+/B2-), children (Experiment 1) and adults (Experiment 2) were tested on the formation of novel simple discriminations (A3+/A2- and B3+/B2-) and conditional stimulus relations between all directly and indirectly paired A stimuli and between all directly and indirectly paired B stimuli (A1-A2-A3, B1-B2-B3). Subjects who formed these sets also received A2-X1 and B1-X2 training followed by a series of probes to assess the formation of two five-member stimulus equivalence classes (A1-A2-A3-X1-Y1, B1-B2-B3-X2-Y2). A modest majority of the children matched the directly paired stimuli (A2-A1, B2-B1 and A1-A2, B1-B2; A2-A3, B2-B3 and A3-A2, B3-B2) with one another while only a few of them also matched the indirectly paired stimuli with one another (A1-A3, B1-B3 and A3-A1, B3-B1). Those who did also related all the A and B stimuli with the designated X and Y stimuli. By contrast, all normal adults matched all paired and conditionally linked stimuli with one another. Present findings and those of related studies on stimulus equivalence are discussed from a stimulus contiguity perspective.