The Influence of Early Sensory and Linguistic Experience on Lexical Development

Abstract

Across four studies, we aim to understand how differential access to perceptual and linguistic information impacts early lexical development. To get traction on this question, we study the early word productions and language environment of young children born deaf or blind. In Chapter 1, we explore why differences in perception and language would influence the developing lexicon. In Chapter 2, we use clinical reports from state early intervention services for Deaf/Hard-of-Hearing (DHH) children to characterize the demographic, audiological, and intervention variability among this population, and identify predictors delays in vocabulary, diagnosis, and intervention. Chapter 3 turns to blind children and provides an in-depth look at the size and composition of early vocabulary, offering insight into how vision influences lexical development. In Chapter 4, we leverage vocabulary data from English-speaking congenitally-blind toddlers and deaf toddlers, relative to their typically-sighted/hearing peers, as well as two sets of deaf children learning American Sign Language. With this unique dataset, we explore how perceptual and linguistic access influence production of words with referents that children cannot physically perceive. Chapter 5 asks whether language input is affected by sensory impairment, with implications for how blind children may utilize the language input to build linguistic knowledge. Summarizing across these studies, we find that both blindness and deafness are associated with spoken vocabulary delays, although the mechanisms likely differ. We find that the magnitude of these delays is sensitive to characteristics of the exact diagnosis, highlighting the need for improved rates of early diagnosis and intervention for particular subsets of these populations. While the composition of vocabulary seems largely resilient to differences in perceptual experience, we find that children are selectively less likely to produce words that are highly and exclusively associated with the impaired modality. Lastly, we find that children’s language environments may differ as a function of their sensory abilities: blind children’s language environments contain longer utterances and less “here-and-now” talk. In conclusion, We show here the resilience of language development to various learning conditions and highlight the importance of language input in providing rich information in the absence of direct perceptual experience. These studies contribute valuable insights into language development in children with sensory impairments but also language development more broadly.