Lexical and Grammatical Factors in Sentence Production in Semantic Dementia: Insights From Greek

Purpose: Language production in semantic dementia (SD) is characterized by a lexical-semantic deficit and largely preserved argument structure and inflection production. This study investigates (a) the effect of argument structure on verb retrieval and (b) the interrelation between inflection marking and verb retrieval in SD. Method: Seven individuals with SD and 7 healthy controls performed 2 sentence elicitation tasks. In Experiment 1, participants described the action taking place in a video. In Experiment 2, they watched the same videos preceded by a phrase prompting the production of past tense. Three verb classes were tested: (a) unergative (e.g., to walk), (b) unaccusative (e.g., to fall), and (c) transitive with 1 object (e.g., to read a book). Results: There was not any quantitative difference among the verb classes in Experiment 1, but error analysis hinted at difficulties related with argument structure complexity. The findings of Experiment 2 suggest no general effect of inflection on verb retrieval; nevertheless, inflection marking impeded the retrieval of verbs with complex argument structure. Large individual variation was established. Conclusions: Argument structure complexity may challenge speakers with SD. Verb retrieval and inflection marking seem to interrelate at the expense of the former. Inflection production may be affected at severe stages of the disease.