Impact of ASL Exposure on Spoken Phonemic Discrimination in Adult CI Users: A Functional Near-Infrared Spectroscopy Study
Date
2024-06-14
Journal Title
Journal ISSN
Volume Title
Publisher
Neurobiology of Language
Abstract
We examined the impact of exposure to a signed language (American Sign Language, or ASL) at different ages on the neural systems that support spoken language phonemic discrimination in deaf individuals with cochlear implants (CIs). Deaf CI users (N = 18, age = 18–24 yrs) who were exposed to a signed language at different ages and hearing individuals (N = 18, age = 18–21 yrs) completed a phonemic discrimination task in a spoken native (English) and non-native (Hindi) language while undergoing functional near-infrared spectroscopy neuroimaging. Behaviorally, deaf CI users who received a CI early versus later in life showed better English phonemic discrimination, albeit phonemic discrimination was poor relative to hearing individuals. Importantly, the age of exposure to ASL was not related to phonemic discrimination. Neurally, early-life language exposure, irrespective of modality, was associated with greater neural activation of left-hemisphere language areas critically involved in phonological processing during the phonemic discrimination task in deaf CI users. In particular, early exposure to ASL was associated with increased activation in the left hemisphere’s classic language regions for native versus non-native language phonemic contrasts for deaf CI users who received a CI later in life. For deaf CI users who received a CI early in life, the age of exposure to ASL was not related to neural activation during phonemic discrimination. Together, the findings suggest that early signed language exposure does not negatively impact spoken language processing in deaf CI users, but may instead potentially offset the negative effects of language deprivation that deaf children without any signed language exposure experience prior to implantation. This empirical evidence aligns with and lends support to recent perspectives regarding the impact of ASL exposure in the context of CI usage.
Description
This article was originally published in Neurobiology of Language. The version of record is available at: https://doi.org/10.1162/nol_a_00143. Copyright: © 2024 Massachusetts Institute of Technology Published under a Creative Commons Attribution 4.0 International
(CC BY 4.0) license (https://creativecommons.org/licenses/by/4.0/)
Keywords
American Sign Language, cochlear implant, fNIRS, language deprivation, signed language, spoken language
Citation
Shakhlo Nematova, Benjamin Zinszer, Thierry Morlet, Giovanna Morini, Laura-Ann Petitto, Kaja K. Jasińska; Impact of ASL Exposure on Spoken Phonemic Discrimination in Adult CI Users: A Functional Near-Infrared Spectroscopy Study. Neurobiology of Language 2024; 5 (2): 553–588. doi: https://doi.org/10.1162/nol_a_00143