For normal language acquisition, children must be able not only to discriminate fine-grained acoustic differences within the speech signal, but also must transform this information into phonological categories relevant to their language. It has been proposed that impairment of a child~s ability to discriminate acoustic-phonetic differences, particularly those stimuli that are brief and rapidly presented and/or acoustically similar; and/or to appropriately categorize this information into phonemic categories can result in disordered language development. Three groups will be studied: 1) children with specific language impairment (SLI) in whom peripheral hearing is entirely normal, but language development is impaired without general cognitive deficits; 2) children with histories of otitis media with effusion (OME), whose peripheral functioning is now normal, but who experienced episodes of mild, temporary hearing loss during the time of language acquisition; and 3) normall developing children, who will serve as controls. Behavioral and electrophysiologic measures will be employed to identify and characterize impaired phonological processing and to determine whether the deficit is due to difficulties in discrimination or to difficulties in identification of phonetic/phonemic information. A passive oddball paradigm to elicit mismatch negativity (MMN) will be used to index preattentive discrimination. Active discrimination and categorization tasks will be used to elicit attention-dependent event-related potentials. The spatiotemporal characteristics of these ERPs to phonetic contrasts will be identified in NL children and then will be employed to characterize the neural correlates of phonemic processing dysfunction in SLI children and those with histories of OME.
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