Discrimination and equivalence class formation in adults using non-differential and differential consequences

ABSTRACT The purpose of the current study was to (1) compare the acquisition of baseline conditional discriminations in younger and older adults, (2) study the effect of the differential outcome procedure (DOP) on the establishment of baseline conditional discriminations, and (3) compare equivalence class formation in younger and older adults. Twenty-four participants, 12 younger adults (20–30 years old) and 12 older adults (67+ years old), participated in the study. In the conditional discrimination training, we gave the participants a break following 180 training trials, and the experimenter evaluated their progress. Participants with overall 50% correct responses or more after those 180 trials continued with the study as planned, with baseline conditional discrimination presented in accordance with the one-to-many (OTM) training structure and serialized training, followed by thinning of programmed consequences across training blocks before a test for the emergence of equivalence classes. If a participant was still training AB-conditional discriminations when the break was presented, with overall correct responses below 50% correct, the participant was exposed to a DOP to evaluate whether such a procedure may facilitate the establishment of the baseline conditional discrimination. Five participants in the older adult group received additional DOP training trials. The results show that two out of the five participants receiving DOP training established the AB baseline conditional discrimination. Neither of those responded in accordance with stimulus equivalence. Two out of the other seven participants in the older adults group and six out of 12 participants in the younger group formed equivalence classes.