Symmetry and Transitivity in Compound Discriminative Stimuli

Abstract

Seventeen adult subjects were trained in a procedure of conditional discrimination between three visual stimuli. Each stimulus was a combination of abstract shapes, displayed horizontally side by side. The experiment was divided into three phases: two training phases and a testing phase. In the first two phases, the subject was to make a choice al each trial between either three stimuli of AB, AC, DE type or three stimuli of BF, BG, HI type. Only AB and BF were reinforced. In the testing phase, subjects were to discriminate again, this time between three stimuli. These triplets of stimuli couId be made up either of stimuli used in the training phases (old stimuli) only, or of new stimuli only. Among the three stimuli of a new triplet, one could be AF, the transitive compound of AB and BF, or FA, the symmetricaI for AF. Intermittent reinforcement was provided for correct discrimination of oId stimulus. No response was reinforced for the new triplets. Results show that among the new tripIets, only the transitive and symmetricaI stimuli are chosen systematically. These results are discussed within the framework of relations between conditional discrimination and simple discrimination of compound stimuli which can be separated.