On the production of irrelevant arguments in agrammatism

We carried out two experiments to see whether there is a possibility that agrammatic aphasics have difficulty in selecting semantic relations of verbs in production. We used picture-description tasks which required subjects to describe pictures with a given verb where the number of objects or people is larger than that of the argument nouns of the verb. The results showed that all the agrammatic subjects produced "irrelevant arguments," i.e., noun phrases with a case particle attached to them which cannot be arguments of provided verbs nor adjuncts and cannot occur with those verbs. The judgment tests requiring the subjects to judge whether sentences with an irrelevant argument were correct or not showed that the subjects' judgment of the grammaticality of those sentences was not normal. The two experiments suggest a possibility that the agrammatic subjects have difficulty in identifying semantic roles of verbs at the level before mapping between semantic roles and grammatical roles.