Carr, D., Wilkinson, K. M., Blackman, D., & McIlvane, W. J. (2000).
Equivalence classes in individuals with minimal verbal repertoires.
Journal of the Experimental Analysis of Behavior,
74, 101-114.
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.
Key words: conditional discrimination, stimulus equivalence,
verbal behavior, touchscreen press, humans