Barnes, D., McCullagh, P., & Keenan, M. (1990). Equivalence class formation in non-hearing impaired children and hearing impaired children. Analysis of Verbal Behavior, 8, 1-11.
The authors, researchers at the University of Ireland and University of Coll, examined the relationship between verbal behavior and stimulus equivalence in 3 sets of children differing in chronological age and verbal ability: non-hearing impaired 3- and 4-yr-olds who had normal verbal skills, severe to profoundly deaf 7- and 8-yr-olds who were rated with verbal ages of above 2 yrs, and severely to profoundly deaf 4- and 5-yr-olds who were rated with verbal ages of below 2 yrs. All Ss were taught a series of 4 conditional discriminations using unfamiliar stimuli; Ss were then tested to determine whether classes of equivalent stimuli had formed. Although all Ss were able to learn the conditional discriminations equally well and all the verbally able children formed equivalence classes, only 1 of the verbally impaired children reliably demonstrated stimulus equivalence formation. Results are consistent with the suggestion that stimulus equivalence and human verbal behavior are closely related.