(Morpho)syntactic comprehension in agrammatic aphasia: Evidence from Greek

Background: A number of hypotheses have been formulated to account for comprehension data in agrammatic aphasia. They explain deficits in comprehending specific structures, such as semantically reversible non-canonical sentences, for example, Trace Deletion Hypothesis (TDH, Grodzinsky, 1986 Grodzinsky, Y. 1986. Language deficit and the theory of syntax. Brain and Language, 27: 135–159. doi:10.1016/0093-934X(86)90009-XCrossref], PubMed], Web of Science ®] , Google Scholar], 1990 Grodzinsky, Y. 1990. Theoretical perspectives on language deficits, Cambridge, MA: MIT Press. Crossref] , Google Scholar], 1995 Grodzinsky, Y. 1995. A restrictive theory of agrammatic comprehension. Brain and Language, 51: 26–51. doi:10.1006/brln.1995.1039Crossref], Web of Science ®] , Google Scholar]), or functional categories, for example, Tree Pruning Hypothesis (TPH, e.g., Friedmann, 2006 Friedmann, N. 2006. Generalizations on variations in comprehension and production: A further source of variation and a possible account. Brain and Language, 96: 151–153. doi:10.1016/j.bandl.2005.06.002Crossref], PubMed], Web of Science ®] , Google Scholar]); Tense Underspecification Hypothesis (TUH, Wenzlaff & Clahsen, 2004 Wenzlaff, M. and Clahsen, H. 2004. Tense and agreement in German agrammatism. Brain and Language, 89: 57–68. doi:10.1016/S0093-934X(03)00298-0Crossref], PubMed], Web of Science ®] , Google Scholar], 2005 Wenzlaff, M. and Clahsen, H. 2005. Finiteness and verb-second in German agrammatism. Brain and Language, 92: 33–44. doi:10.1016/j.bandl.2004.05.006Crossref], PubMed], Web of Science ®] , Google Scholar]); Interpretable Features’ Impairment Hypothesis (IFIH; e.g., Varlokosta et al., 2006 Varlokosta, S., Valeonti, N., Kakavoulia, M., Lazaridou, M., Economou, A. and Protopapas, A. 2006. The breakdown of functional categories in Greek aphasia: Evidence from agreement, tense, and aspect. Aphasiology, 20: 723–743. doi:10.1080/02687030500513703Taylor & Francis Online], Web of Science ®] , Google Scholar]). Several studies, however, report evidence contradicting these theories (e.g., Caramazza, Capasso, Capitani, & Miceli, 2005 Caramazza, A., Capasso, R., Capitani, E. and Miceli, G. 2005. Patterns of comprehension performance in agrammatic Broca's aphasia: A test of the Trace Deletion Hypothesis. Brain and Language, 94: 43–53. doi:10.1016/j.bandl.2004.11.006Crossref], PubMed], Web of Science ®] , Google Scholar]; Dickey, Milman, & Thompson, 2008 Dickey, M. W., Milman, L. H. and Thompson, C. K. 2008. Judgment of functional morphology in agrammatic aphasia. Journal of Neurolinguistics, 21: 35–65. doi:10.1016/j.jneuroling.2007.08.001Crossref], PubMed], Web of Science ®] , Google Scholar]) and propose new accounts to explain the comprehension deficits in agrammatic aphasia, for example, Distributed Morphology Account (DMA, Dickey et al., 2008 Dickey, M. W., Milman, L. H. and Thompson, C. K. 2008. Judgment of functional morphology in agrammatic aphasia. Journal of Neurolinguistics, 21: 35–65. doi:10.1016/j.jneuroling.2007.08.001Crossref], PubMed], Web of Science ®] , Google Scholar]).

Aims: Against the background above, this study investigates the ability of three Greek-speaking agrammatic individuals to comprehend a wide range of structures and functional categories: semantically reversible (canonical) active and (non-canonical) passive sentences, Complementizer Phrase, subject-verb Agreement, Tense, and Aspect.

Methods & Procedures: We administered: (a) two sentence-picture matching tasks to test comprehension of reversible active and passive sentences, and Tense; (b) a sentence grammaticality judgement task to test judgement of Tense, Aspect, and subject-verb Agreement; and (c) a picture-pointing task to test comprehension of Complementizer Phrase.

Outcomes & Results: (a) Two of the three agrammatic participants performed at chance on reversible passive sentences and above chance on active sentences. The third participant performed equally high on the two sentence types. Two participants performed at chance on Tense comprehension and one above chance. (b) The three participants were selectively or across-the-board impaired in judgement of Agreement, Tense, and Aspect. One of the two selectively affected participants had chance performance on Aspect and above chance performance on Agreement and Tense. The other one performed at chance on Aspect and Tense, and above chance on Agreement. The third participant's performance was equally poor on all three categories. (c) All three agrammatic participants performed above chance on the comprehension of Complementizer Phrase.

Conclusions: In comprehension/judgement, canonical and non-canonical sentences do not dissociate in all agrammatic speakers, while functional categories associated with the verb morphology may be compromised in the face of relatively well-preserved categories that are located higher in the syntactic hierarchy. All three agrammatic participants support the DMA, and two of them support the TDH. Instead, none of them provided support to the TPH, TUH, and IFIH.