Effects of Stimulus Discriminability on Discrimination Acquisition and Stimulus-Equivalence Formation: Assessing the Utility of a Multiple Schedule

Abstract

A multiple schedule was used to examine the effects of stimulus discriminability on discrimination acquisition in baseline and subsequent stimulus-equivalence formation. Six college students were exposed in two experiments to more or less discriminable stimuli across multiple-schedule components (reinforcer magnitude was unequal and equal in Experiments 1 and 2, respectively). For five of the six participants, slower baseline acquisition occurred with the less discriminable stimuli. After high accuracy scores occurred in both components for several sessions, stimulus equivalence was tested across multiple sessions. In terms of accuracy, delayed emergence of equivalence formation only occurred in the component with the less discriminable stimuli for three of the five participants who previously displayed differential acquisition. For one of these other two participants, a 2-week follow-up assessment revealed that stimulus equivalence was disrupted only in the component previously correlated with the slower acquisition period. In terms of response latency, slower responding was obtained in the component with the less discriminable stimuli for all six participants, particularly during initial equivalence testing. These results demonstrate that stimulus discriminability can influence both discrimination acquisition and stimulus-equivalence formation. The results also support the utility of examining stimulus-equivalence formation using a multiple schedule.