Processing of verbal inflection in subjects with agrammatic aphasia: a case study

CAMILA STECHER; MARÍA ELINA SÁNCHEZ; JAICHENCO, VIRGINIA

Conferencia; Words in the World International Conference; 2020

The Words in the World-Social Sciences and Humanities Research Council of Canada

People with agrammatic aphasia (PWAA) present a language disorder caused by a brain injury. There is substantial cross-linguistic evidence that morphosyntax of verbs is impaired in agrammatic aphasia and that not all verb inflections are affected equally, with tense morphology being especially vulnerable (Benedet et al., 1998; Caramazza& Hillis, 1991, among others). The reasons for this dissociation are still under discussion. The Tree-Pruning Hypothesis (-TPH- Friedmann &Grodzinsky, 1997), asserts that the problem is due to a pruning of the syntactic tree at the Time node, but if this were to be the case, Agreement should also be impaired. Following this idea, Gavarró& Martínez-Ferreiro (2007) suggest that Agreement would be spared because the relation would hold between V and a functional category other than T when T is pruned (taking the sentential structure proposed in Cinque, 1999), but they don?t explain how this process would take place.Our work aims to study these difficulties that exist in agrammatic aphasia to obtain evidence on its processing in Spanish, a morphologically complex language that uses two different morphemes to express time and agreement in verbal inflection, to see if the performance pattern is similar to that accounted on the literature (specifically Argentinian Spanish, in which inflected, simple tenses are preferred over their complex counterparts, in opposition to what happens in peninsular Spanish). To this end, we developed abrand-new battery of tests specially designed to tap every aspect of this issue. Here, we will analyze the performance of one spanish-speaking person with agrammatic aphasia (BG) in two of those tests. First, a sentence-completion task in which the participant had to produce an inflected verb within a model sentence that was previously provided, according to a change on the time-reference or the subject of the sentence. We found that she only gave correct answers for 12 out of the 50 stimuli, 11 corresponding to agreement items and only one to tense items. We also tested a control group of 20 people with the same educational level and mean age and found a ceiling effect with their mean correct answers being 49.9/50. So far, our results show a clear deficit in the processing of verbal inflection in this patient compared to that of the control group, with a marked difference between tense (more severely deteriorated) and agreement, according to what we expected. Second, we are now testing the same participants in a sentence-picture matching task, with 40 items divided into two experimental conditions (corresponding to tense and agreement). The results will soon be available.We also wanted to discuss the current theoretical explanations for this deficit and review them in the light of newer theories on morphosyntax. In this sense, we believe that adopting the Distributed Morphology framework (Embick, 2015) could be enriching, since it poses that Agr (agreement) morphemes are added to the structures in a postsyntactic affixation operation at the Phonological Form (PF) branch of the grammar, prior to Vocabulary Insertion, in order to meet language-specific well-formedness requirements. If the different morphemes are added in different stages, it could be expected for them to have a different pattern of impairment. Thus, the proposal of the TPH, within this framework, could be adequate to account for this particular deficit.