Saunders, R. R., Drake, K. M., & Spradlin, J. E. (1999).
Equivalence class establishment, expansion, and modification in preschool children.
Journal of the Experimental Analysis of Behavior,
71, 195-214.
Preschool children were taught four two-choice match-to-sample
conditional discriminations with 10 arbitrary visual stimuli. For
6 participants, 2 of the 10 stimuli served as the sample, or
conditional, stimuli in all discriminations. For 5 additional
participants, the same pair of stimuli served as the
discriminative, or comparison, stimuli in all discriminations.
Equivalence classes were established with more participants in
the latter group, replicating prior research with participants
with retardation. Four participants, in whom equivalence classes
were established and who were available for further
participation, were exposed to new conditional discriminations
without trial-by-trial feedback and involving some novel and some
familiar stimuli. Consistent conditional responding was observed,
and tests for inclusion of the novel stimuli in the original
classes showed class expansion. Training to reverse the
unreinforced conditional performances produced a reversal of
class membership in 3 of 4 participants, an outcome not
consistent with other studies. The results are discussed with
respect to the interaction of class structure and size.
Key words: stimulus equivalence classes, equivalence relations,
unreinforced conditional selection, matching to sample,
conditional discrimination, preschool children