Class size effects on the maintenance of equivalence relations with an intra-group design

Like the formation of equivalence classes, their maintenance is affected by diverse experimental variables. The present study aimed to analyze the effect of class size on the formation and maintenance of equivalent stimuli classes with an intra-group design. A matching-to-sample procedure was used to teach to 21 undergraduate students three sets of three equivalent stimuli classes with three, four, and five stimuli. The teaching sequence of the different class’s sizes was randomized to control order effects. This variable did not affect the results. All 21 participants showed class consistent responses in a Mixed Test conducted after the conditional relations acquisition. Six weeks after the Mixed Test, the maintenance of the equivalence relations was tested. It was observed that 3, 6 and 8 participants continued to show more than 90% of correct responses on the Maintenance Test, when classes had 3, 4 and 5 stimuli, respectively. It was concluded that class size didn’t affect the formation of equivalence classes, but it affected their maintenance. Keywords: conditional discrimination; stimulus equivalence; matching-to-sample; undergraduate students; stability; class size.