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Language in profoundly deaf people with schizophrenia

Research output: ThesisDoctoral Thesis

Published
Publication date2013
Number of pages237
QualificationPhD
Awarding Institution
  • University Of Cambridge
Supervisors/Advisors
  • McCarthy, Rosaleen McCarthy , Supervisor, External person
  • McKenna, Peter, Supervisor, External person
  • du Feu, Margaret, Supervisor, External person
  • Russell, James, Supervisor, External person
Thesis sponsors
  • The Church of Greece
  • The Wingate Foundation
  • Cambridge European Trust: George & Marie Vergottis Foundation
  • Fitzwilliam College (E.D. Davies Scholarship)
  • Experimental Psychology Society
Award date26/10/2013
Publisher
  • University of Cambridge
Original languageEnglish

Abstract

Schizophrenia is known to occur in prelingually profoundly Deaf individuals with probably the same frequency as in the hearing population. However, the impact of Deafness on the clinical features of schizophrenia is an under-researched area. The current thesis aims to provide the first comprehensive analysis of the ways schizophrenia manifests itself in Deaf adults, with particular reference to language disorders.

Study 1 empirically tested a clinical observation that motor dexterity for sign was preserved despite there being impairment in motor skill for purposes other than language in schizophrenia. 15 profoundly Deaf sign-using schizophrenic patients and 28 matched profoundly Deaf healthy volunteers were given specially devised measures for motor skill in linguistic and non-linguistic tasks. The study supported the hypothesis that there is a dissociation between relatively preserved motor skill for sign language and impaired motor skill for non-linguistic gestural tasks. This study also produced an incidental observation: the Deaf schizophrenic patients appeared to make frequent errors in handshape, which in the context of the study implied abnormality in production of a particular linguistic element of sign language, classifiers.

The aim in Study 2 was to further examine Study 1’s finding of abnormality in the production of handshapes in classifier construction, specifically to replicate it under controlled conditions and establish whether it is more pronounced than in other aspects of language. The performance of a second group of 14 profoundly Deaf signing schizophrenic patients and 35 Deaf healthy volunteers was recorded based on a battery of measures testing classifier and noun comprehension and production. This confirmed Study 1’s finding of errors in classifier production in Deaf schizophrenic patients and provided qualified support for the hypothesis that the impairment was more marked for production than comprehension, and more marked for classifiers than for nouns.

Taking the results of the analyses of both studies together, the present thesis suggests that motor abnormalities are present in Deaf schizophrenia in the face of relatively intact motor skill for language. Despite its motor intactness, however, certain aspects of sign language in Deaf schizophrenia seem to be disproportionately affected than others. This primarily applies to the production of handshape in classifier construction. These results suggest that schizophrenia affects language production in Deaf patients with schizophrenia in unique ways.