Selective treatment of regular versus irregular verbs in agrammatic aphasia: Efficacy data

This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material. Background: Production of verb morphology, especially tense marking, is frequently impaired in persons with agrammatic aphasia. Very little research has examined theoretically driven treatments for verb morphology deficits in aphasia. Aims: This study examined the relative efficacy of using regular (wash-washed, rob-robbed) versus irregular (drink-drank, keep-kept) verbs as stimuli to treat morphological impairments in individuals with aphasia. This comparison was motivated by differences in the lexical organisation of regular and irregular verbs proposed in psycholinguistic theory. Methods & Procedures: A single-participant multiple-baseline design was used to examine treatment outcomes in six individuals with agrammatic aphasia. Participants received training to produce tense morphology using only either regular or irregular verbs, and the crucial outcome measure was generalisation to untrained past tense forms (regular to irregular and vice versa). Outcomes & Results: All participants improved in the trained tenses and generalised to the production of regular tense morphology on untrained verbs. Generalisation to untrained irregular past tense was relatively modest, irrespective of whether regular or irregular verbs were trained. Conclusions: The results replicate previous findings that verb morphology deficits respond to intervention, and extend the findings by suggesting that choice of stimuli may have consequences for generalisation effects. The implication for aphasia rehabilitation is that tense training using irregularly inflected verbs generalises to a greater variety of untrained verb inflections (including regular past) than does the use of regular verbs.