Spoken word processing and the effect of phonemic mismatch in aphasia

Abstract

To cite this Article Janse, Esther(2010) 'Spoken word processing and the effect of phonemic mismatch in aphasia', Aphasiology, 24: 1, 3 -27, First published on: 24 November 2008 (iFirst) To link to this Article: DOI: 10.1080/02687030802339997 URL: http://dx.doi.org/10.1080/02687030802339997Full terms and conditions of use: http://www.informaworld.com/terms-and-conditions-of-access.pdf This article may be used for research, teaching and private study purposes. Any substantial or systematic reproduction, re-distribution, re-selling, loan or sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden.The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material. Spoken word processing and the effect of phonemic mismatch in aphasiaEsther JanseUtrecht University, The NetherlandsBackground: There is evidence that, unlike in typical populations, initial lexical activation upon hearing spoken words in aphasic patients is not a direct reflection of the goodness of fit between the presented stimulus and the intended target. Earlier studies have mainly used short monosyllabic target words. Short words are relatively difficult to recognise because they are not highly redundant: changing one phoneme will often result in a (similar-sounding) different word.Aims: The present study aimed to investigate sensitivity of the lexical recognition system in aphasia. The focus was on longer words that contain more redundancy, to investigate whether aphasic adults might be impaired in deactivation of strongly activated lexical candidates. This was done by studying lexical activation upon presentation of spoken polysyllabic pseudowords (such as procodile) to see to what extent mismatching phonemic information leads to deactivation in the face of overwhelming support for one specific lexical candidate. Methods & Procedures: Speeded auditory lexical decision was used to investigate response time and accuracy to pseudowords with a word-initial or word-final phonemic mismatch in 21 aphasic patients and in an age-matched control group. Outcomes & Results:Results of an auditory lexical decision task showed that aphasic participants were less sensitive to phonemic mismatch if there was strong evidence for one particular lexical candidate, compared to the control group. Classifications of patients as Broca's vs Wernicke's or as fluent vs non-fluent did not reveal differences in sensitivity to mismatch between aphasia types. There was no reliable relationship between measures of auditory verbal short-term memory and lexical decision performance. Conclusions: It is argued that the aphasic resu...

Decreased Sensitivity to Phonemic Mismatch in Spoken Word Processing in Adult Developmental Dyslexia

“…In other words, they had serious difficulty rejecting words with mispronunciations in both initial and final position. Again, it should be noted that aphasia affects speech processing to a much more severe extent than dyslexia: the performance difference between the control and pathological group was much greater in Janse (2010) than in the present results. The dyslexic adults did not differ in accuracy from the controls for the final mismatches, which suggests that they could compensate for their subtle speech decoding problems if they had been able to focus on one lexical candidate in particular.…”

“…Indeed, a moderate and significant correlation is attested between non-word repetition accuracy (taken as a measure of verbal short-term memory, see Table 2) and lexical decision accuracy (collapsed over all mismatch conditions) for the dyslexic participants (Spearman's rho = .578, p = .006). This moderate correlation between a verbal short-term memory task and lexical decision performance was stronger than found for aphasic patients (Janse 2010). On the basis of these findings, the question arises whether dyslexia is characterised by poor phonological representations or by poor processing of phonological information to achieve lexical access.…”

“…The material was a subset of the material used in a similar study on sensitivity to phonemic mismatch in aphasia (Janse 2010). Since the speech processing deficit was assumed to be less severe in dyslexia than in aphasia, we only investigated the minimal-mismatch conditions in the present study (and left out pseudowords in which the phonemic mismatch involved more than one phonetic feature).…”

“…The present study focused on mispronounced words to investigate whether lexical activation in dyslexic adult listeners is equally sensitive to phonemic mispronunciations in longer spoken words (e.g., in a pseudoword such as procodile) as in a control group of age-and education-matched listeners. A similar approach was taken in a study on lexical activation in aphasic listeners (Janse 2010). Even though the two language pathologies are very different in terms of cause and severity, we had the opportunity to test the two groups with the same language materials.…”