Assessing Infant Speech Discrimination Using Pupillary Dilation Response
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Date
2024-08
Authors
Heilenbach, Sam
Journal Title
Journal ISSN
Volume Title
Publisher
University of Oregon
Abstract
Perceptual narrowing is central to the ability of infants in acquiring language competency. The broad sensitivity seen in younger infants to even the smallest units of speech – phonemes – becomes fine-tuned toward the end of their first year of life to the specific phonemes of their native language(s), enabling them to partition continuous speech into discrete words, essential for acquiring language proficiency. Perceptual narrowing refers to the gradual reduction in sensitivity to phonetic contrasts that are not relevant in the native language, along with an enhanced ability to recognize and distinguish phonetic contrasts that are meaningful in the native language. Understanding the timing and mechanisms of this process is key to understanding speech and language development more broadly. Current methods for studying perceptual narrowing rely on behavioral methods that require lengthy training periods, which result in high rates of attrition and may resultingly limit the generalizability of these findings. This study investigated the potential of sound-induced pupil response (SIPR) to measure infant speech-sound discrimination. We hypothesized that SIPR will accurately index auditory discrimination changes as perceptual narrowing unfolds. Using a mixed factorial-design, infants aged 10-12 months were exposed to native and non-native phonetic contrasts while their pupil responses were measured. Our sample of pilot data provides clear evidence validating SIPR as a sensitive measure of infant response to language. However, the sample is as yet too small to offer conclusive findings regarding perceptual narrowing. In any case, the SIPR holds great promise as a new, highly sensitive tool for investigating language development in early infancy. Thus, the significance of this research lies in its potential to enhance our understanding of developmental change in early auditory discrimination abilities.
Description
40 pages
Keywords
development, pupillometry, audition, psychophysics, cognition