An experimental analysis of auxiliary and copula verb generalization in aphasia.

Two subjects with chronic Broca's aphasia were taught to produce third person singular auxiliary is in sentence contexts to determine if is production would generalize to untrained auxiliary is items and to copula is contexts. A single subject (ABAB) reversal design was employed. Results revealed that training a few exemplars of the present tense auxiliary is resulted in generalized responding to untrained auxiliary is and copula is plus predicate adjective items. Generalized responding to untrained copula is plus predicate nominative and locative items was marked by individual variability. Although auxiliary and copula is verb production was maintained on 2- and 6-week follow-up probes, transfer to spontaneous speech was negligible. The results were interpreted as providing partial support for the existence of a functional or generative response class between verbal auxiliary and the copula is verbs.