A Developmental Approach to Assessing and Treating Agrammatic Aphasia

Purpose: There is mounting evidence that the agrammatism that defines Broca’s aphasia can be explained in processing terms. However, the extant approach simply describes agrammatism as disparate deficits in a static, mature system. This tutorial aims to motivate and outline a developmental alternative. This alternative is processability theory (PT), a root-to-apex theory of language development, with its origins in the field of second language acquisition, which can connect the findings of aphasia research. Method: This tutorial critically reviews research on agrammatism as a language deficit, a representational deficit, and a processing phenomenon. Given evidence from research applying PT to language disorders, this tutorial outlines PT’s multidimensional architecture of language processing. Using an emergence (onset) criterion, PT predicts fixed developmental stages in word order (syntax) and inflection (morphology) and individual differences in the timing of syntax and morphology. To link PT to agrammatism, this theory’s applications to diagnosis and teaching are overviewed, and a case study of five individuals with moderate agrammatism is presented. Results: Analysis showed that all individuals were positioned in the early PT stages and differed in their timing of syntax and morphology consistent with theoretical predictions. Conclusions: Evidence from the case study suggests that, although agrammatism results from neural damage and associated language loss, the processing procedures necessary for relearning remain and can be exploited for recovery. A program of diagnosis and intervention is proposed, and future research directions are discussed