Verb production and word order in Russian agrammatic speakers

Background: Verb production has been shown to be impaired in individuals with agrammatic Broca's aphasia. Several theories have linked this deficit to problems with the implementation of grammatical information that the verb contains. In particular, the number and type of arguments associated with a verb were suggested as causes of production difficulties in agrammatic speakers. The influence of these two factors on agrammatic production has been investigated in English and Dutch (Bastiaanse Van Zonneveld, 2005; Thompson, 2003). Aims: The present study focuses on exploring these factors in a structurally different language. Russian, with its rich morphology and relatively free word order, is of interest because it enables not only testing of earlier advanced hypotheses on agrammatic production, but also specification of them at some essential points. Methods Procedures: A sentence production priming paradigm was used that was based on the method developed by Thompson, Lange, Schneider, and Shapiro (1997) which allows a particular verb and sentence construction to be elicited. Six conditions included sentences with different numbers of arguments (one or two), different types of thematic role mapping (direct or indirect), and different word order (basic or scrambled). The test contained 60 items, 10 items per condition. In all, 16 individuals with agrammatic aphasia and 16 non-brain-damaged individuals participated in the study. Outcomes Results: Cross-linguistic significance of the earlier advanced hypotheses was demonstrated: the increased number of verb arguments and syntactic operations concerning constituent movement cause production problems for Russian agrammatic speakers. Moreover, the data show that agrammatic speech difficulties are related to the number of arguments explicitly mentioned in a sentence, to the number of operations applied to the syntactic structure of a produced sentence, and to changing the base-generated position of a constituent (not to the order of the constituents per se). Conclusions: The study provides further evidence that verb production is selectively impaired in agrammatic aphasia. This deficit is related to the implementation of the grammatical information that a verb contains and the syntactic operations applied to basic structures.