Elika Bergelson

Part of language development necessarily involves connecting sensory inputwith linguistic units. We asked whether visual input in particular was differ-entially relevant for learning words and building grammar. While substan-tial prior work (e.g. Bates & Goodman, 1997) confirms a tight link betweengrammar and the lexicon, there could in principle be different degrees ofreliance on a visual referential world across them. To begin to tackle thislarge question, we examined the productive morphosyntax skills of youngblind children (N=28, 14-55mo.), each matched to a sighted child of thesame productive vocabulary size, based on a parent-reported vocabulary andearly grammar checklist. We asked whether blind children’s morphosyntacticskills were similar, advanced, or delayed relative to sighted vocabulary-size-matched peers. We found no differences between blind and sighted childrenacross 6 morphosyntax measures. Blind children did show a delay in produc-tive morphosyntax skills relative to sighted children, and this delay (roughly9 months) was statistically longer than the delay reported for spoken vo-cabulary in this same group (Campbell, Casillas, & Bergelson, 2024). Wealso found that both age and vocabulary strongly predicted morphosyntaxscores for sighted children, but only vocabulary size (and not age) robustlypredicted morphosyntax for blind children. These results extend seminalresearch in early language development in blind and sighted children (e.g.Landau & Gleitman, 1985), highlighting close vocabulary to syntax links inearly childhood across groups, and supporting the idea that vision does notcontribute separably to either facet of language development.

The emergence of canonical babbling is a critical milestone that predicts later spoken language outcomes, often varying in timing and frequency in children with neurodevelopmental diagnoses. However, measuring when and how often children babble canonically has historically required time-intensive manual annotation and specialized expertise. Here, we tested an automated pipeline for measuring vocal maturity from daylong audio recordings. The pipeline identifies child vocalizations using a speaker segmentation algorithm, transcribes them into the International Phonetic Alphabet using BabAR (a multilingual phoneme recognition system), and derives vocal maturity estimates from the resulting transcripts. We compared this pipeline’s performance against manual annotation using 220 daylong recordings from 157 U.S. children 4-60 months across four groups: children with Angelman (n = 39), Down (n = 45), and fragile X (n = 20) syndromes, and children with no known diagnoses or genetic risk factors (n = 53). Automatic vocal maturity estimates, operationalized as canonical proportion (CP, the proportion of canonical vocalizations), correlated strongly with manual estimates per-group and overall (Pearson’s r between 0.90 and 0.98). Automated and manual estimates also converged on the same pattern of CP trajectories: low risk children demonstrated rapid early gains; children with Down and fragile X syndromes showed slower upward trajectories; and those with Angelman syndrome exhibited downward trajectories. Our approach reduces months of manual annotation to overnight processing, making existing large-scale datasets, such as LENA® recordings, reusable and opening vocal development research to larger, more diverse populations.

We investigated how experience with particular nouns and referents influences infant word comprehension by combining home recordings with in-lab eyetracking. In Study 1, infants (n=44) participated in a yearlong longitudinal study which included monthly home recordings (daylong audio and hourlong video, 6-17mo.) and hand-tailored eyetracking experiments (every two months, 8-18mo.). Word comprehension was operationalized as how much more infants looked at named images than distractors. Each session tested 16 words: 8 held constant across all infants at each timepoint ("generic" common nouns, e.g., "shoe"), and 8 hand-picked for each session from each child's recent home recordings. Of the hand-picked items, half appeared as images familiar to children from home (e.g., their own ball); the other half and all generic items appeared as prototypical child-friendly (but not individually-tailored) images. Results showed expected improvements with age, and an effect of word frequency (particularly at 12 and 14mo. timepoints) but not referent familiarity. In Study 2 (n=247), cross-sectional controls completed the same eyetracking experiments (i.e., those hand-tailored for Study 1 children) as a stronger test of the roles of frequency and referent familiarity. Here, we did find an effect of referent familiarity. Study 2 infants understood words less well than those in Study 1, particularly when tested with images of referents selected from Study 1 children's homes. Together, these findings highlight the role of experience in shaping early noun comprehension and suggest that once infants understand words, they readily generalize them to new instances beyond those they are familiar with.

Prior work finds that some elements of language input or skills during infancy and toddlerhood predict later language skills. Here, we ask if combining these two sources of information about early language development improves predictions of language outcomes, using a longitudinal data set that captures early language input and abilities over the first 5 years in a sample of 44 American English-learning children. While several early language skills significantly predicted later language skills (Spearman's ρ = 0.44-0.63, p < .05), most infant input measures did not. Notably, the most robust predictor of preschool language was parent-reported productive vocabulary at 1.5 years. This suggests that early language assessments (e.g., parental-reported vocabulary) can be reliable measures of language skills with high predictive value for longer term language outcomes. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

In many circumstances, age and experience with language go hand in hand, making it challenging to disentangle their roles in early word learning. Here we use shared book-reading as a vehicle for structured but naturalistic language exposure, allowing us to control age of exposure to new words (i.e. novel nouns). We presented 18-month-olds (n = 24) and 22-month-olds (n = 20) with three novel nouns embedded in a picture book that caregivers read at home over two weeks. Caregiver-child reading sessions were audio-recorded and coded for toddlers’ novel noun production (our outcome measure), and properties of the reading sessions (such as reading session length and extratextual extensions beyond the book text). While 18-month-olds' and 22-month-olds' caregivers said the target words the same number of times during book-sharing, the older toddlers' caregivers engaged in longer reading sessions and used more extratextual extensions. Over the two weeks, nearly all 22-month-olds and over 2/3 of 18-month-olds produced at least one of the novel nouns (and most 22-month-olds produced all 3). Intriguingly, increased caregiver extratextual extensions were associated with a higher likelihood of toddlers producing novel words during reading sessions within each age group, and overall. In addition, toddlers’ overall productive vocabulary (based on a parent-report checklist, the MBCDI) predicted novel word production among 22-month-olds but not 18-month-olds. Together, these findings show that two weeks of naturalistic book-sharing (with about 250 exposures to each of 3 novel nouns) is sufficient to foster new word production. Our results reveal both developmental changes in toddlers’ learning capacities over 18 to 22 months, and the efficacy of certain aspects of caregiver input across this range. Caregivers’ extratextual talk during shared book-reading emerged as a particularly potent support for toddlers’ use of newly learned words even at the earliest stages of productive vocabulary development.

Our original paper (Liu, Hilton, et al., 2023) found effects of linguistic experience on music perception which generalized across a half-million speakers of fifty-four languages. In a critique, Creel (Creel, 2026) claims that our multilevel modelling approach biased the language-level estimates such that languages with small-sample sizes “spuriously appear to pattern consistently” compared to “raw” sample means. We respectfully disagree and counter this claim here.

This study compared spoken language input to deaf/hard of hearing (DHH) children with cochlear implants, and two sets of hearing controls: age and hearing-age matches. Using daylong audio-recordings from 6-32 month-olds (n=16/group), we examined whether systemic variation in thirteen language input metrics predicted children’s emerging language outcomes. Language input to the DHH group contained shorter sentences and more auditory words (e.g., “loud”) than input to hearing-age-matches, and slightly fewer adult words than input to age-matches. Despite the modest input differences, DHH children produced fewer mature vocalizations than age-matched peers; their vocalizations also increased less robustly with age. Regression models indicated that age, hearing status, noise, input quantity, overlapping speech, and input MLU collectively predicted >50% of variance in children’s vocal maturity. These results suggest differences in children’s access to language input play a larger role than the relatively small systematic input differences across DHH and hearing children.

This study investigates the development of canonical proportion (CP), an indicator of speech development, across diverse language and environmental contexts. Using the Speech Maturity Dataset (SMD) comprising 366 children, aged 0;2–6;4, across 10 different languages and cultures, we explore the influence of multilingual exposure, language syllable complexity, and community type (industrialised, non-industrialised) on CP. We find that monolingual children display higher CP measures than their multilingual peers. In addition, CP is higher for children learning languages with simple syllable complexity than those with more complex syllables. We also find no significant differences in the CP trajectory of children from industrialised versus non-industrialised communities. Integrating these findings in the broader literature, we highlight the importance of diversifying participant samples to capture the complex relationship between language exposure, social environment, and language development.

Individual differences in early language input are rampant but hard to quantify without resource-intensive naturalistic recordings, posing a challenge for testing links between individual experience and facets of language development like vocabulary growth. We tested whether a quick parent survey on infants’ exposure to common nouns could reliably predict nouns’ frequency in home-recordings (testing its validity) and children’s own vocabulary (testing input-learning links). In Study 1 (n=44; 95% White, 5% mixed-race) we gathered monthly home recordings and exposure surveys every two months from 8-18mo. Parent reported exposure to each noun (16/timepoint, 5-point scale) was compared to the noun’s relative frequency in infants' home-recordings, and to comprehension and production of each noun via parent vocabulary survey (CDI). Reported exposure significantly predicted noun frequency in home recordings. It also predicted both reported noun comprehension and production, even after accounting for age. Results from an age- and gender-matched cross-sectional sample (Study 2, n=264, 78% White, 11% mixed-race, 11% other) with the same vocabulary and exposure surveys were consistent, supporting generalizability. These findings suggest a brief word-exposure survey can reliably estimate individualized word input and knowledge, at least for highly common nouns. This method complements naturalistic recordings and corpus-based norms by capturing individual variation and enabling more scalable research across linguistic and sociocultural contexts.

This paper describes a dataset consisting of manually annotated nouns from a corpus of longitudinal day-long audio and hour-long video recordings collected monthly from 44 babies from age 6 months to age 17 months. This dataset was created as part of a larger project, called SEEDLingS, that examines the development of iinfants’ language comprehension before and after their first birthday, from earliest comprehension to the early days of word produc tion. This paper provides an overviewof the corpus, describes how and why the nouns from the corpus were annotated, and discusses considerations for reuse of this dataset for future work. The described annotations and relevant metadata are publicly available alongside this manuscript.