Inflectional Morphology in Fluent Aphasia: A Case Study in a Highly Inflected Language

Inflectional morphology difficulties are typically reported in non-fluent aphasia with agrammatism, but a growing number of studies show that they can also be present in fluent aphasia. In agrammatism, morphological difficulties are conceived as the consequence of impaired phonological encoding and would affect regular verbs more than irregular verbs. However, studies show that inflectional morphology difficulties concern both regular and irregular verbs, and that their origin could be more conceptual/semantic in nature. Additionally, studies report more pronounced impairments for the processing of the past tense compared to other tenses. The goal of this study was to characterize the impairment of inflectional morphology in fluent aphasia. RY, a 69-year-old man with chronic fluent aphasia completed a short neuropsychological and language battery and three experimental tasks of inflectional morphology. The tasks assessed the capacity to select the correct inflected form of a verb based on time information, to access the time information included in an inflectional morpheme, and to produce verbs with tense inflection. His performance was compared to a group of five adults without language impairments. Results showed that RY had difficulties selecting the correct inflected form of a verb, accessing time information transmitted by inflectional morphemes, and producing inflected verbs. His difficulties affected both regular and irregular verbs, and verbs in the present, past, and future tenses. The performance also shows the influence of processing limitations over the production and comprehension of inflectional morphology. More studies of inflectional morphology in fluent aphasia are needed to understand the origin of difficulties.