Equivalence class formation influenced by the number of nodes separating stimuli

Two experiments examined whether the number of nodes separating stimuli influenced human subjects' conditional discrimination performances. In Experiment 1, 3 college students were taught visual conditional discriminations among 2 seven-member stimulus classes using a single-sample/two-comparison procedure. Following training, subjects were exposed to repeated probes for the emergence of derived relations separated by varying numbers of nodes. For all three subjects the results indicated that the order in which derived relations emerged was consistent with the number of nodes separating stimuli. The second experiment sought to extend Experiment 1 with four college students by teaching visual conditional discriminations among 3 seven-member stimulus classes using a single-sample/three-comparison procedure. Results from the repeated probes in Experiment 2 were similar to those of Experiment 1. The two experiments demonstrate that the number of nodes separating stimuli influences the order in which derived relations emerge during equivalence class formation.