Short-term adaptation to sound statistics is unimpaired in developmental dyslexia.

Yafit Gabay,Lori L Holt

doi:10.1371/journal.pone.0198146

Yafit Gabay, Lori L Holt

Open Access

https://doi.org/10.1371/journal.pone.0198146

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Journal: PloS one	Publication Date: Jun 7, 2018
Citations: 9	License type: CC BY 4.0

Affiliation: University of Haifa, Carnegie Mellon University

Abstract

Developmental dyslexia is presumed to arise from phonological impairments. Accordingly, people with dyslexia show speech perception deficits taken as indication of impoverished phonological representations. However, the nature of speech perception deficits in those with dyslexia remains elusive. Specifically, there is no agreement as to whether speech perception deficits arise from speech-specific processing impairments, or from general auditory impairments that might be either specific to temporal processing or more general. Recent studies show that general auditory referents such as Long Term Average Spectrum (LTAS, the distribution of acoustic energy across the duration of a sound sequence) affect speech perception. Here we examine the impact of preceding target sounds’ LTAS on phoneme categorization to assess the nature of putative general auditory impairments associated with dyslexia. Dyslexic and typical listeners categorized speech targets varying perceptually from /ga/-/da/ preceded by speech and nonspeech tone contexts varying. Results revealed a spectrally contrastive influence of the preceding context LTAS on speech categorization, with a larger magnitude effect for nonspeech compared to speech precursors. Importantly, there was no difference in the presence or magnitude of the effects across dyslexia and control groups. These results demonstrate an aspect of general auditory processing that is spared in dyslexia, available to support phonemic processing when speech is presented in context.

Highlights

Developmental dyslexia is a specific developmental disorder in learning to read that is not a direct result of impairments in general intelligence, gross neurological deficits, uncorrected visual or auditory problems, emotional disturbances or inadequate schooling [1]
In light of observations that individuals with dyslexia have phonological processing impairments [2], difficulty forming perceptual anchors [9], inefficiencies in learning across probabilistic information [16, 17] and dysfunction in forming short-term representations across sound statistics [11, 12], these characteristics make context-dependent speech categorization across precursors varying in long-term average spectrum (LTAS) a potentially useful tool for examining the nature of impairment in dyslexia
We examine speech categorization in the context of preceding speech and nonspeech contexts differing in LTAS among adults with developmental dyslexia

Summary

Introduction

Developmental dyslexia is a specific developmental disorder in learning to read that is not a direct result of impairments in general intelligence, gross neurological deficits, uncorrected visual or auditory problems, emotional disturbances or inadequate schooling [1]. In light of observations that individuals with dyslexia have phonological processing impairments [2], difficulty forming perceptual anchors [9], inefficiencies in learning across probabilistic information [16, 17] and dysfunction in forming short-term representations across sound statistics [11, 12], these characteristics make context-dependent speech categorization across precursors varying in LTAS a potentially useful tool for examining the nature of impairment in dyslexia. The processing demands this paradigm places on auditory and speech processing make it possible that speech processing may not be impacted by context sounds’ LTAS among individuals with developmental dyslexia. We examine speech categorization in the context of preceding speech and nonspeech contexts differing in LTAS among adults with developmental dyslexia

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Results