Sentence comprehension in Malay-speaking adults with aphasia: the role of affix integration

Background: One of the impairments in comprehension mostly reported for aphasia is that in reversible passive sentences, where a systematic asymmetry with reversible active sentences has been attested across languages. In several accounts, this selective impairment has been proposed to be the result of the specific syntax of passive sentences. However, some results particularly from flexible word order languages suggest that a pattern where both active and passive sentences are impaired also exists. Aims: In this study, we examined the actives and passives in the comprehension of a flexible word order language, namely standard Malay, in people with aphasia (PWA), aiming to confirm that the predominant pattern in this language is one of generalised impairment across reversible sentences (active and passive), and not an asymmetrical one. The role of fluency in determining the pattern of impairment was also explored. Methods & procedures: Fourteen healthy adults and 20 PWA, 14 with fluent aphasia and 6 with non-fluent aphasia, took part in a comprehension study in standard Malay. Standard Malay is a flexible word order language that relies on the parsing of the voice affix on the verb to correctly interpret both active and passive sentences. Participants were tested on a sentence-picture matching task on comprehension of active and passive reversible clauses. Outcomes and results: The study revealed that PWA were overall less accurate than healthy speakers in comprehension of reversible active and passive sentences, and non-fluent PWA were less accurate than fluent PWA with no effect of sentence type (active/passive). While not predominant, an asymmetric pattern was present in some participants. We propose that an impairment in thematic role assignment leads to a generalised impairment in comprehension of reversible sentences, while preserved thematic role mapping and impaired syntax lead to an asymmetric impairment. Conclusions: The study confirmed that speakers of Malay mostly show a generalised impairment in both active and passive sentences. Given the nature of the language, we propose that this suggests that impairment in Malay is predominantly shown on affix integration, first in mapping of thematic roles, and then in the full syntactic processing.