The Formation of Stimulus Equivalences: Fear-Relevant Versus Fear-Irrelevant Stimulus Classes

Abstract

Investigation was given to the effects of two different types of stimuli on the formation of three-member (A→B→C) stimulus equivalence classes. In Condition 1, snake-related stimuli were tested; and in Condition 2 flower-related stimuli were examined. Stimuli in the two sets were matched in terms of the number of letters in each stimulus, letter placement, and word frequency. Fifty-one female subjects participated in a stimulus equivalence modified matching-to-sample training format adapted from Fields, Adams, Verhave, and Newman (1990). Using a crossover design that controlled for serial order effects, subjects received conditional discrimination training and emergent relations testing with both stimulus sets. Results revealed significant interaction between the formation of stimulus equivalence classes and stimulus sets. Stimulus set consistent test performances were achieved more slowly for stimuli composed of fear-relevant stimuli.