The effect of syntactic frequency on sentence comprehension in standard Indonesian Broca's aphasia

Background: Comprehension of reversible sentences that have derived word order has often been reported as impaired in agrammatic aphasia. Most accounts of this phenomenon refer to the syntactic differences between derived and base word order of the arguments. However, it has been demonstrated that in agrammatic spontaneous speech in standard Indonesian (SI) passives are produced at a rate that is proportional to that of healthy speakers. The main difference between passives in SI and in other languages is the frequency with which passives are used: passives in SI are highly frequent. The high frequency can be explained by the fact that passives are used for politeness reasons, saliency of the passive morphology, earlier acquisition, and formal simplicity of the passive structure.Aims: The purpose of the current study is to investigate comprehension of the passive as a derived structure in SI and the influence of frequency.Methods & Procedures: A sentence-to-picture matching task was developed to test four reversible sentence types (active, passive, subject cleft and object cleft). There are three variables that are of interest, that is, word order, embedding and relative frequency of structures. Eleven agrammatic speakers classified as suffering from Broca's aphasia were tested.Outcomes & Results: The passive sentences were comprehended equally well as the active sentences. Embedding had limited effects: subject clefts were understood as well as actives and passives. Object clefts, however, were understood poorly and significantly worse than the three other sentence types.Conclusions: The sentence comprehension deficit pattern shown in SI individuals with Broca's aphasia introduces frequency of a syntactic structure as an additional factor to consider. Whether frequency or pragmatic constraints protects against erosion of the passive in Broca's aphasia in SI remains an open question.