Syntactic Comprehension in Persian-Speaking Agrammatics: Further Proof of Trace Deletion Hypothesis

Abstract

So far, there have been three important theories explaining the nature and extent of grammatical deficit in agrammatic aphasia. In this respect, while the two mainly performance-based theories of agrammatics, i.e. trade-off hypothesis (TOH) and mapping hypothesis (MH), provide a very broad account of this deficit, the trace deletion hypothesis (TDH) presents a much narrower stance on the nature of the deficit as well as on the question of modularity. This research, being the first one in the Persian context, tries to test this theory in four gender-, education-, and age-matched Persian-speaking agrammatics and the same matched controls via executing a grammatical judgment test. For the purpose of evaluating our participants’ performance, 90 pairs of sentences, composed of well-formed and ill-formed ones, were presented to the subjects in a randomized manner, based on which participants were supposed to express their opinions regarding their grammaticality in a grammatical judgment task. The types of sentences being testified included active agentive, object cleft, subject cleft, agentive passive, psychological passive and object WH-constructions. Our findings, in line with the predictions of TDH, indicated that agrammatics faced many challenges with constructions in which constituent movements are involved. In contrast, their comprehension remained intact in agentive constructions. The theoretical and psychological implications of the findings are discussed.