Morphosemantic treatment of inflection of verb tense in Persian-speaking aphasic patients with agrammatism: a single-subject study

Abstract

ABSTRACT Background The production of verb inflection, especially tense marking, is commonly impaired in persons with agrammatic aphasia. In Persian, verbs are inflected in three tenses the past, present, and future, and play a key role in the sentence.A group of theories attributes verb inflection errors to syntactic or semantic deficits in sentence formulation. Aims The present study intends to investigate the effect of morphosemantic treatment on the inflection of regular and irregular verbs in the past, present, and future tenses in Persian-speaking agrammatic participants. Methods & Procedure A single-subject study with an ABA design was performed to evaluate the effect of morphosemantic treatment on four Persian-speaking agrammatic participants. In the current study, in addition to presenting descriptive statistics and visual analysis, percent of non-overlapping data (PND) was used to determine whether there was an effect of intervention during the treatment phase, and d1 statistics of effect size analysis was used to determine whether there was a maintenance effect during the withdrawal phase. Outcomes & Results All participants demonstrated significant improvement in the trained regular and irregular tenses and generalized to the production of tense morphology on untrained regular and irregular verbs. The effect of therapy was maintained for a three-week follow-up. Also, the morphosemantic intervention was associated with an increase in most narrative measures and language tests scores. Conclusions Therapy for verb inflection in spontaneous speech is clinically important. The current study demonstrated that morphosemantic intervention could be successfully used for tense marker deficits in Persian-speaking participants with aphasia and agrammatism.