Impoverishment of grammatical features in a non fluent aphasic speaker : the grammatical nature of minimal structures

The present study is an examination of an Italian aphasic speaker (M.R.) with non-fluent speech following a focal lesion in the left hemisphere. We develop an explanation of M.R.'s language impairment compatible with theories of generative syntax and with some observations on parsing strategies. The explanatory framework we adopt considers the grammar to be an integral part of on-line language processing. A series of experiments was run across modalities (production, comprehension and grammaticality judgment), with the aim of defining impaired linguistic structures grammatically. Results of the various experiments show selective impairment in some selective configurations involving object movement in relative clauses, in Wh-questions and in clitic object constructions. Comprehension deficit of non canonical sentences has been attested since Caramazza and Zurif's seminal work (1976). In the present case-study a similar subject/object asymmetry emerges from interrogative sentence production, which have been found to be selectively impaired for object movement of animate arguments. An interesting data was obtained testing attraction effects with clitics and prepositional modifiers. M.R. does not manifest attraction effects if a clitic object is a potential intervenier of the relevant agreement relation; prepositional modifiers induce a significative attraction effects. We will speculate on these effects has precise phenomena related to syntactic conditions on minimal structures. This case study lends support to the hypothesis that the present linguistic deficit is an impoverishment of procedural capacities. This impoverishment is grammatically driven, and it manifests itself in reduced syntactic structures. M.R.'s linguistic competence is not different to a non-impaired grammatical system. M.R. has the capacity to analyse sentences respecting syntactic phrase structures but not in the way normal speakers do. Crucially, this approach to aphasia does not assume the existence of a specific grammatical deficit, as the so-called agrammatism. 7 Summary of findings In the theoretical linguistic model (Chomsky, 2000) the language faculty is