The breakdown of Japanese passives and theta-role assignment principle by Broca's aphasics.

Syntactic comprehension of various types of passive sentences by Japanese Broca's aphasic patients was investigated. Based on their performance on the so-called "possessive passive" and "indirect passive," we exemplified that the comprehension abilities of Broca's aphasics and agrammatic Broca's aphasics point to a distinction between the gapped and gapless passive, as is proposed in Kubo (1990). We proposed a new structural account of syntactic disorders in Japanese, based on the assumption that the Head parameter, the directionality parameter of theta-assignment, and the distinction between the internal argument and external argument are retained in the grammar of Broca's aphasics. We then demonstrated that Broca's aphasics interpret sentences by the argument structure of a predicate and by the canonical direction of the theta-assignment. It was also shown that the proposed principle can account for the Broca's aphasics' performance on other types of constructions and that it has many consequences for the language-universal account of syntactic deficits.