ABSTRACT
Psychologists have long recognized that certain aspects of human behavior, such as language, reasoning, and problem solving, may develop in the absence of direct training. Psychologists are faced with the challenge of accounting for such untrained verbal and cognitive skills. Stimulus equivalence is demonstrated when the stimulus elements of at least two interconnected conditional relations display the properties of reflexivity, symmetry, and transitivity. The property of reflexivity is demonstrated when participants match any stimulus of a prospective class to an identical stimulus without differential reinforcement. The stimuli employed in most equivalence research are Greek letters or arbitrary geometric forms. The experimenter-provided relations among the stimuli are arbitrary. The materials were matching-to-sample exercises presented in a paper-and-pencil format, incorporating training and subsequent testing. Analysis was restricted to students whose probe performances showed that they had memorized the original relations, on the premise that it is futile to probe for the equivalence properties of nonacquired relations.
