Abstract
To study equivalence class formation in elderly persons, ten people 13- to 74-years old received training of the conditional discriminations required for equivalence and testing of symmetry, transitivity, and equivalence. First, samples A1 or A2 were randomly presented with comparisons B1 and B2; selections of B1 in the presence of A1 and selections of B2 in the presence of A2 were reinforced. Then, B1 or B2 were the sample and C1 and C2 were the comparisons; selections of C1 in the presence of B1 and selections of C2 in the presence of B2 were reinforced. Later, trials of these baseline discriminations were alternated with other trials in which former samples were the comparisons and former comparisons were the samples (e. g., B1 and B2 alternated as samples and A1 and A2 were the comparisons) but selections were not reinforced —symmetry tests. Also, probes in which A1 or A2 were the samples and C1 and C2 were the comparisons were presented without reinforcement —transitivity test. Finally, sample C1 or C2 and comparisons A1 and A2 were presented in other unreinforced trials —equivalence test. The four 13-to-53-years elderly people and two people older than 64 responded with almost no errors to the tests of symmetry; the remaining 4 people responded initially with errors but finally demonstrated symmetry. All participants, but one, made almost no errors in the probes of transitivity and equivalence. Thus, stimulus equivalence was demonstrated in elderly people. A comparison between the performance in the training and in the tests of transitivity and equivalence showed that elderly people remembered (had contextual recognition) less than younger adults in training trials but remembering was not affected in tests for stimulus equivalence.
