Browsing by Author "Bergelson, Elika"

Children learn hundreds of words in a few short years (e.g., Dale & Fenson, 1996; Fernald, Pinto, & Swingley, 1998), but there is wide variability between children (Fenson, 2007). Some of the variability in children’s language skills can be attributed to differences in their language input (e.g., generally, children who hear more words say more words; Huttenlocher, et al., 1991; Huttenlocher, et al., 2010). However, there are many other factors at play that may influence both children’s language input and their ability to learn from that input over time, such as their own cognitive, social, and linguistic developments (Bergelson, 2020). In this dissertation, I ask if differences in infants’ language input explain changes in their word comprehension, explain gender differences in their early language skills, or predict their later language outcomes years later.

In Chapter 1, I review prior work on variation in children’s language experience, how it maps onto their developing language skills, and how children’s own development may affect that input. Chapter 2 investigates how children's word comprehension develops across infancy in an eye-tracking study and a complementary corpus analysis. I find that infants gain semantic precision in word comprehension from age 0;6 to 1;6, but this improvement is not readily explained by changes in their at-home exposure to the tested words. Instead, children's improvements in word comprehension may be driven by cognitive and social developments that aid their word learning. Chapter 3 investigates if differences in children's early language input could drive gender differences in their early language skills. I replicate prior work finding girls have an early word production advantage, but I do not find evidence that they have different language input compared to boys. However, I find that children hear more words once they've said their first word, regardless of gender. These results suggest that children's language input does not vary by gender, but instead by their language abilities. In Chapter 4, I turn to investigating a longer timescale of language input and development. Do children's early language abilities and input in infancy predict their later language outcomes years later? I find that children's early language skills consistently predict their later language skills, and measures of children's early language input do not improve our predictions. In Chapter 5, I summarize and synthesize the results of these three studies and discuss implications and future directions of this work.

Across these three studies, I find that language input is not a strong predictor of differences in children’s language skills. Instead, my results suggest that other factors (such as children’s age, gender, and earlier language development) better predict children’s language outcomes.

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.

When learning a language, typically-developing infants face the daunting task of learning both the sounds and the meanings of words. In this dissertation, we focus on a source of variability that complicates the one-to-one relationship between words and their meanings: wordform variability. In Chapter 1 we make a distinction between the micro timescale, where learning and acquisition can be observed during the comprehension of individual utterances, and the macro timescale, where a longitudinal lens can reveal intuitions about the speech that infants and toddlers can learn from. In Chapter 2, a corpus analysis confirms that infants hear more irregular verbs than irregular nouns. We then compare toddlers' phonological representations of irregular nouns and verbs to their regular counterparts in an eyetracking study. Toddlers demonstrate well-specified representations for verbs 8 months later than they do for nouns, but the sounds in irregular words are represented with high fidelity at the same time as regular words in both syntactic categories. In Chapter 3, an eyetracking study with adults explores word comprehension when coarticulation cues have been manipulated. Adults take available referents into account when they hear a word whose coarticulation cues match an unfamiliar word. We also find that participants vary in whether they map an unfamiliar word to an available unfamiliar object if the unfamiliar word is sufficiently similar to a relevant known word. In Chapter 4, we return to early childhood, using annotated data from a longitudinal corpus of naturalistic recordings from the lives of 6-17-month-old infants. In this corpus, we characterize and quantify wordform variability, and find that for high-frequency words, wordform variability may aid in word learning. Theoretical implications and next steps are discussed in Chapter 5. Taken together, this work suggests that throughout the lifespan, wordform variability is no problem for learners and can in some cases facilitate learning and comprehension.