Thirty-two subjects completed 2 stimulus equivalence tasks using a matching-to-sample paradigm. One task involved direct reinforcement of conditional discriminations designed to produce derived relations between self-referring stimuli (e.g. , me, myself, I) and positive evaluation words (e.g., whole, desirable, perfect). The other task was designed to produce derived relations between selfreferring stimuli and negative evaluation wordls (e.g., unworthy, flawed, inadequate). Performance on each task was recorded via response latency and percent correct. Prior to completion of the equivalence tasks, subjects completed 2 self-report measures: the Outcome Ouestionnaire-45 (00-45) and the Rosenberg SelfEsteem Scale (RSE) . Subjects were divided into groups based on their 00-45 score (high or low distress) and FISE score (high or low self-esteem). Significant differences in percent correct were found between both the 00-45 groups and the RSE groups. Subjects who reported high distress and a negative sense of self made significantly more errors on the tests for equivalence for the task that required matching self-referential stimuli with positive evaluation words .
Stimulus EquivalenceMurray Sidman conducted the first systElmatic investigation of stimulus equivalence in 1971. In this well-cited study, an individual with a learning disability was taught to identify pictures of objects given the spoken words. He was then taught to identify the written words given the spoken words. Without any additional training, the individual matched the pictures to the written words and the written words to the pictures. That is, he derived relations among the stimuli in the absence of direct reinforcement for the specific choices, responding to the stimuli as if they were equivalent. Sidman referred to this behavioral phenomenon as Correspondence may be directed to Rhonda M. Merwin ,