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Distinguishing Between Phonological Output Buffer Deficit and Apraxia of Speech: Error Analysis to the Rescue

EasyChair Preprint no. 6492

3 pagesDate: August 31, 2021



When a patient produces phoneme errors, it is challenging to decide whether they result from apraxia of speech (AOS) or from a phonological output buffer (POB) deficit (Haley et al., 2013).

Studies found that individuals with POB deficits produce words (and nonwords) with phoneme errors but substitute/omit/add whole morphological affixes, number words, and function words, so that they may substitute a whole unit with another whole unit of the same kind (Dotan & Friedmann, 2015). We examined whether this phenomenon could serve as a basis for a differential diagnosis between POB deficits and AOS. The POB immediately follows the phonological output lexicon in the lexical processing, so it may still enjoy lexical feedback, whereas AOS affects later stages. We therefore examined whether individuals with POB deficits show advantage for the production of existing words in comparison to nonwords whereas individuals with AOS show similar production of words and pseudowords.


The participants were 7 individuals who produced phonological errors in spontaneous speech, repetition, naming, and reading aloud. Their production of nonwords, morphologically simple and complex words, number and function words was tested in tasks of repetition, oral reading, and naming.


Both groups produced phonological errors in the root phonemes. However, the 4 POB-impaired individuals substitute or omit whole morphological affixes, whole number words, and function words; the 3 individuals with AOS made phoneme errors even within affixes and number words. Furthermore, individuals with POB deficit showed better production of words compared to pseudowords, whereas individuals with AOS showed no lexicality effect.

This study offers a novel way to distinguish between AOS and a POB-deficit.

Keyphrases: aphasia, apraxia of speech, morphological affixes, phonological errors, phonological output buffer, speech errors

BibTeX entry
BibTeX does not have the right entry for preprints. This is a hack for producing the correct reference:
  author = {Aviah Gvion and Hadar Saadya and Naama Friedmann},
  title = {Distinguishing Between Phonological Output Buffer Deficit and Apraxia of Speech: Error Analysis to the Rescue},
  howpublished = {EasyChair Preprint no. 6492},

  year = {EasyChair, 2021}}
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