Purpose: Developmental dyslexia (DD) has mostly been attributed to arise from phonological impairments; however, several theories indicate a temporal processing deficit as the underlying cause of DD. So far, research examined the influence of temporal cues on concurrent speech sound categorization in DD, but effects of temporal information from a context (e.g., speaking rate) on the perception of subsequent sounds (i.e., “rate normalization”) have not been considered. This study examined whether individuals with DD are capable of implicitly extracting temporal information embedded in context and use it for phoneme categorization to the same extent as healthy readers. Method: Fifteen individuals diagnosed with DD and 16 healthy readers, all native speakers of Hebrew, listened to context sentences followed by target words. They had to indicate whether the target word sounded more like taam (“taste”; a long-vowel response) or tam (“naïve”; a short-vowel response). Temporal information of the context was manipulated (slow vs. fast speaking rate sentences) as well as the vowel duration of the target in a 5-step continuum. Results: Listeners with DD did use the rate context to inform their decisions but to a significantly lesser extent than healthy listeners. In addition, their categorization of the vowel duration continuum was somewhat less distinct than that of the control group. Conclusions: Individuals with DD are impaired not only in tasks involving direct temporal processing, as shown in previous studies but also in the use of temporal information of a context that impacts the perception of subsequent target words. This inability to fully utilize rate normalization processes may influence the formation of abstract phonological representations in individuals with DD.
Bibliographical noteFunding Information:
This study is part of the research conducted at the University of Haifa, by Inaas-Jana Najjar, as partial fulfillment of her requirements for a master?s degree under the supervision of Yafit Gabay. This project was funded by a grant from the German Research Foundation (Grant RE 3047/1-1) to the third author We would like to thank Shai Gabay and Rosa Franzke for their help with preparing the speech materials, Almog Shurkey for testing participants, and Jessica Siddins for proofreading the article.
This study is part of the research conducted at the University of Haifa, by Inaas-Jana Najjar, as partial fulfillment of her requirements for a master’s degree under the supervision of Yafit Gabay. This project was funded by a grant from the German Research Foundation (Grant RE 3047/1-1) to the third author.
© 2019 American Speech-Language-Hearing Association.
ASJC Scopus subject areas
- Language and Linguistics
- Linguistics and Language
- Speech and Hearing