Infants are sensitive to statistics in spoken language that aid word-form segmentation and immediate mapping to referents. However, it is not clear whether this sensitivity influences the formation and retention of word-referent mappings across a delay, two real-world challenges that learners must overcome. We tested how the timing of referent…

The boundary effect, namely the infants' failures to compare small and large numerosities, is well documented in studies using visual stimuli. The prevailing explanation is that the numerical system used to process sets up to 3 is incompatible with the system employed for numbers >3. This study investigates the boundary effect in 10-month-old…

Studying early language development has been a challenging task throughout the years. Earlier studies mostly documented language competence only after toddlers had started producing their first words. Theoretical and methodological advances in this domain brought about more sophisticated ways of probing into early development by exploiting overt…

The early language environment, especially high-quality, contingent parent-child language interactions, is crucial for a child's language development and later academic success. In this secondary analysis study, 89 parent-child dyads were randomly assigned to either the Music Together® (music) or play date (control) classes. Children were 9- to…

Psycholinguistic research on children's early language environments has revealed many potential challenges for language acquisition. One is that in many cases, referents of linguistic expressions are hard to identify without prior knowledge of the language. Likewise, the speech signal itself varies substantially in clarity, with some productions…

Maria Montessori's work remains popular and influential around the world. She provided fascinating descriptions of her observations of children's learning. Yet at the heart of her work is a lacuna: the issue of how children learn their first language. For Montessori, it was a marvel, a miracle--but a mystery. We argue that the later philosophy of…

When infants hear sentences containing unfamiliar words, are some language-world links (such as noun-object) more readily formed than others (verb-predicate)? We examined English learning 14-15-month-olds' capacity for linking referents in scenes with bisyllabic nonce utterances. Each of the two syllables referred either to the object's identity,…

This longitudinal study investigated parents' different pretend play behaviors (substitution, animation, and role enactment) to their infants during free play and the bidirectional links with infants' vocabulary development at 14 months (Time-1: N = 34, M[subscript age] = 14.23 months) and 20 months (Time-2: N = 34, M[subscript age] = 20.33…

Infants' sensitivity to transitional probabilities (TPs) supports language development by facilitating mapping high-TP (HTP) words to meaning, at least up to 18 months of age. Here we tested whether this HTP advantage holds as lexical development progresses, and infants become better at forming word--referent mappings. Two groups of 24-month-olds…

Infants begin to produce abstract "math" words -- such as numbers (e.g., "two"), spatial terms (e.g., "down"), and magnitude words (e.g., "more") -- during their second postnatal year. Math words, as all words, are likely learned in the home setting during interactions with caregivers. However, everyday…

Communication is commonly viewed as connecting people through conscious symbolic processes. Infants have an immature communication toolbox, raising the question of how they form a sense of connectedness. In this article, we propose a framework for infants' communication, emphasizing the subtle unconscious behaviors and autonomic contingent signals…

Developmental psychology focuses on how psychological constructs change with age. In cognitive development research, however, the specifics of this emergence is often underspecified. Researchers often provisionally assume linear growth by including chronological age as a predictor in regression models. In this work, we aim to evaluate this…

In low- and middle-income countries, urbanization has spurred the expansion of peri-urban communities, or urban communities of formerly rural residents with low socioeconomic status. The growth of these communities offers researchers an opportunity to measure the associations between the level of urbanization and the home language environment…

Maternal sensitivity during an observed mother-child clean-up task at 18 months and maternal sensitivity during an observed mother-child free-play task at 18 months were tested as independent predictors of child internalizing symptoms, externalizing symptoms, social competence, and language development at 24 months. Participants (n = 292 mothers)…

Infants' preference for vowelharmony (VH, a phonotactic constraint that requires vowels in a word to be featurally similar) is thought to be language-specific: Monolingual infants learning VH languages show a listening preference for VH patterns by 6 months of age, while those learning non-VH languages do not (Gonzalez-Gomez et al., 2019; Van…