Equivalence classes in individuals with minimal verbal repertoires

UMMS Affiliation

Shriver Center



Document Type


Medical Subject Headings

Adolescent; Adult; Discrimination Learning; Female; Humans; Language Tests; Male; *Mental Retardation; Nonverbal Communication; Touch; *Verbal Behavior


Mental and Social Health


Studies from two different laboratories tested for equivalence classes in individuals with severe mental retardation and minimal verbal repertoires. In the first study, 3 individuals learned several matching-to-sample performances: matching picture comparison stimuli to dictated-word sample stimuli (AB), matching those same pictures to printed letter samples (CB), and also matching the pictures to nonrepresentative forms (DB). On subsequent tests, all individuals immediately displayed Emergent Relations AC, AD, BC, BD, CD, and DC, together constituting a positive demonstration of equivalence (as defined by Sidman). The second study obtained a positive equivalence test outcome in 1 of 2 individuals with similarly minimal verbal repertoires. Taken together, these studies call into question previous assertions that equivalence classes are demonstrable only in individuals with well-developed language repertoires.

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Citation: J Exp Anal Behav. 2000 Jul;74(1):101-14. Link to article on publisher's site

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Link to Article in PubMed

PubMed ID