The role of morphology in the comprehension of wh-dependencies in Croatian aphasic speakers

Abstract

Background: Recent research on the comprehension of subject and object wh-questions in English Broca's aphasic speakers has shown the existence of a specific pattern: subject and object who questions, as well as subject which NP questions, are comprehended above chance, while object which NP questions are comprehended at chance. Since English is a strict word-order language, the subject–object asymmetry is identified as an asymmetry both in word order and in thematic role assignment. The present study investigated the comprehension of wh-dependencies in Croatian, which is a language with relatively free word order that does not necessarily associate thematic roles with specific syntactic positions. Aims: The goal of the study was to determine whether the pattern of comprehension of wh-dependencies that has been reported for English Broca's aphasic speakers is also exhibited by Croatian aphasic speakers. We hypothesised that due to the role of morphological features such as case in sentence comprehension in a free word-order language like Croatian, aphasic speakers of that language would exhibit a different pattern. Methods & Procedures: We tested the comprehension of six types of wh-dependencies formed with tko “who” and koji “which” (direct, embedded, long-distance with za, long-distance without za, and passivised questions, and relative clauses with koji) in six Croatian aphasic speakers. All participants had had a lesion to the left hemisphere: three of them were Broca's aphasic speakers and three were mixed cases of non-fluent aphasia. Outcomes & Results: The main finding of the study is that Croatian Broca's aphasic speakers do not exhibit the same subject–object asymmetry that has been reported for English Broca's aphasic speakers. Some asymmetry was found in the three patients with mixed aphasia, whose comprehension was better on object- than subject-extracted structures. Conclusions: The asymmetric pattern found in the cases of mixed aphasia runs in the opposite direction to the asymmetry typically reported in the literature. Relying on cross-linguistic findings from the processing-based research on subject–object comprehension asymmetries in neurologically intact populations we assume that, in Croatian, thematic roles are assigned directly to case-marked arguments without the mediation of syntactic information, and propose a morphological account of the Croatian data based on the validity of case cues in MacWhinney and Bates' competition model.