Phonological simplifications, apraxia of speech and the interaction between phonological and phonetic processing

Claudia Galluzzi, Ivana Bureca, Cecilia Guariglia, Cristina Romani*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Research on aphasia has struggled to identify apraxia of speech (AoS) as an independent deficit affecting a processing level separate from phonological assembly and motor implementation. This is because AoS is characterized by both phonological and phonetic errors and, therefore, can be interpreted as a combination of deficits at the phonological and the motoric level rather than as an independent impairment. We apply novel psycholinguistic analyses to the perceptually phonological errors made by 24 Italian aphasic patients. We show that only patients with relative high rate (>10%) of phonetic errors make sound errors which simplify the phonology of the target. Moreover, simplifications are strongly associated with other variables indicative of articulatory difficulties - such as a predominance of errors on consonants rather than vowels -but not with other measures - such as rate of words reproduced correctly or rates of lexical errors. These results indicate that sound errors cannot arise at a single phonological level because they are different in different patients. Instead, different patterns: (1) provide evidence for separate impairments and the existence of a level of articulatory planning/programming intermediate between phonological selection and motor implementation; (2) validate AoS as an independent impairment at this level, characterized by phonetic errors and phonological simplifications; (3) support the claim that linguistic principles of complexity have an articulatory basis since they only apply in patients with associated articulatory difficulties.

Original languageEnglish
Pages (from-to)64-83
Number of pages20
JournalNeuropsychologia
Volume71
Early online date13 Mar 2015
DOIs
Publication statusPublished - 1 May 2015

Bibliographical note

Copyright: 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.

Funding: British Academy.

Keywords

  • apraxia of speech
  • conduction aphasia
  • markedness
  • phonological impairments
  • phonological simplifications
  • phonological/phonetic interactions

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