Models and Approaches for Characterizing Aphasia: Psychological and Epistemological Perspectives

NORA SILVANA VIGLIECCA

Encyclopedia of Linguistics

Nova Science Publishers

Año: 2019; p. 1 - 46

Aphasia is a neurogenic condition while language is not. In the aphasia field, the direction of reasoning should go from brain injury to verbal impairment; the logical implication is one-way. When the logical implication is inverted, the conclusion is false. This principle allows predicting wrong inferences when the reasoning goes in the reverse order. Maybe that was the cause of the impasse suffered on the matter for more than a century and a half. When prospective approaches are not possible, and trying to attenuate the deficits of retrospective ones, then all the patients should undergo the same psychological evaluations. Post-mortem aphasia studies are always retrospective. Curiously, they are still taken as ?definite?. Aphasia patterns have to be discovered independently of their biological basis in order to avoid circularity; besides, any combination of the latent language impairments has to be recognized. New models concerning the relationship between brain and language have emerged. Beyond the novelty of the instrument used for data collection, deep methodological considerations are necessary not only for discovering the dissociations and interactions among neuropsychological functions, but also for studying the consistency among the different approaches, samples and instruments employed. Nowadays, such consistency has been magnified by dissemination. The impetus to reach consensus with psychological events has led to the shocking situation in which an article published in 1984, for example, has been quoted almost 22,000 times by April of 2015 as synonymous with the procedure for demonstrating diagnosis. Considering the guidelines of 2011 for primary progressive aphasia (PPA) that number was almost 800 in just four years. If the conceptual and the operational definitions are confused, the theory gets into an endless loop. Additionally, the use of typical cases seriously restricts progress. Despite significant improvements observed in the psychological methods during the last years, the psychological outcomes are still puzzling. The ?comprehension-expression? organization and the ?semantics- syntax? one involve two different systems of classification which are not mutually excluding. Unlike the dissociation between comprehension and expression, the dissociation between semantics and syntax is not easy to observe, even using complex linguistic evaluations. Syntax involves relationships among semantic units but, simultaneously, produces a higher-order semantic unit. Researchers evaluate those levels of ?semantic? units to differentiate semantics vs. syntax. The methodology is unclear because changing parts involves changing the whole. Neuropsychology has two parts. If the validity of the psychological outcomes is doubtful, any language neurobiological model will be doubtful.