Words in infant-directed speech (IDS) are often phonetically reduced. This likely renders words harder for infants to learn and recognize. This difficulty might be mitigated by the repetitive nature of IDS, in particular if reduced instances are often preceded by clear instances (i.e., the first-mention effect). To characterize phonetic clarity in American English word repetitions, words were extracted from the IDS of eight mothers and presented to adults (n = 36) who judged their clarity. First mentions of repeated words were found to be clearer than second mentions, though this effect was small. Clarity was rated as greater for less common words and for utterance-final words. Clarity was also greater for words parents thought their child knew. The results help guide intuitions about the phonetic problem infants face when learning their first words.

A growing literature explores the representational detail of infants’ early lexical representations, but no study has investigated how exposure to real-life acoustic-phonetic variation impacts these representations. Indeed, previous experimental work with young infants has largely ignored the impact of accent exposure on lexical development. We ask how routine exposure to accent variation affects 6-month-olds’ ability to detect mispronunciations. Forty-eight monolingual English-learning 6-month-olds participated. Mono-accented infants, exposed to minimal accent variation, detected vowel mispronunciations in their own name. Multi-accented infants, exposed to high levels of accent variation, did not. Accent exposure impacts speech processing at the earliest stages of lexical acquisition.

Deaf and hard-of-hearing (DHH) preschoolers have difficulty comprehending and producing English plural morphology. This study investigated their comprehension and production of the plural at primary-school age using novel words, to better understand their mental representation of plural morphology. Thirty 5- to 9-year-old DHH children and 31 children with normal hearing (NH) completed a two-alternative forced-choice comprehension task and a wug production task. Performance was not significantly poorer for DHH children, though some morphophonological contexts proved challenging for both groups. Performance was correlated with vocabulary size. This suggests that, if DHH children have sufficient vocabulary, they may perform like primary school NH peers in plural comprehension and production.

Demonstratives and locative adverbs cross-linguistically are typically acquired relatively late, with children initially overusing proximal forms. However, these findings are largely based on research in languages with only two or three demonstratives. It is unclear whether the findings extend to languages with more complex systems. The present study examines data from Inuktitut, a language of the Inuit-Yupik-Unangan family, which has 20 demonstrative roots and 10 locative adverb roots representing six spatial distinctions. It uses data from 18 Inuktitut speakers (8–60 years) to investigate the target-like use of demonstratives/locatives and data from eight Inuktitut-speaking children (1–4 years) and their mothers to determine the acquisition trajectories of these structures. Children initially used only the proximal demonstratives/locatives, which aligns with prior research. The proportion of proximal forms out of all others decreased significantly with mean length of utterance in morphemes (MLUm), and by MLUm 2.50, children were using the full demonstrative/locative paradigm in a target-like manner. This differs from prior research and highlights the importance of language diversity in acquisition research.

Arabic emphatic consonants are claimed to be late-acquired, likely due to their motoric complexity, involving both coronal and pharyngeal/uvular constrictions. Children’s production has largely been studied using impressionistic data, with limited acoustic analysis. This study acoustically examines the acquisition of emphatic consonants in Saudi-Hijazi Arabic-speaking children aged 3–6 years. Thirty-eight children performed a real-word repetition task, after which consonantal and vocalic cues to the plain–emphatic contrast were measured. Results show that children produce both types of acoustic cues, with an age-related increase in the acoustic contrast and an overall alignment with adult patterns. Larger acoustic contrasts were found in vowels preceding rather than following consonants in word-medial positions, with no evidence for a difference between word-initial and word-final positions. The plain–emphatic contrast was greater for stops than fricatives and larger for female than male children. These findings are discussed in relation to the development of coarticulated consonants.

The current study probes Mandarin-learning toddlers’ sensitivity to two grammatical noun phrase orders differing in typological markedness. With three visual fixation experiments, we find that by age 2;6, children distinguish the cross-linguistically common order – but not the typologically rare one – from an ungrammatical order; however, their sensitivity to the two grammatical orders does not differ significantly. Further, we conduct a corpus analysis and demonstrate that for early acquisition, both grammatical orders are neither sufficiently nor consistently supported in the linguistic input. The sensitivity patterns and input profile outlined in our study constitute the first step of testing, in a natural language setting, a bias for typologically common ordering discussed in the artificial language learning literature. Although the findings remain inconclusive, they underscore the potential for future investigations in this direction.

This longitudinal study investigates the changes in bilingual oral language proficiency and home language and literacy practices of young Chinese American and Mexican American dual language learners (DLLs) before and during the COVID-19 pandemic. Given that DLLs represent a significant portion of young children in the U.S., often facing socioeconomic challenges, understanding their language development is crucial. The pandemic’s considerable impact on the educational trajectories of low-income immigrant communities is of particular concern. The sample comprised 132 DLLs (41 Mexican Americans and 91 Chinese Americans) from low-income immigrant families. Data on oral language proficiency in English and the home language and home literacy practices were collected before the pandemic and again 1.5 years later. Despite school closures, both groups showed improved oral language proficiency and shifts in home literacy practices over time. This study reveals distinct relationships between home literacy practices and oral language proficiency in the two immigrant groups.

Recent research has shown that 6-month-olds relate novel words suffixed with -s, like babs, that are embedded in passages, with just the stem bab, demonstrating an early sensitivity to morphological relatedness. This study builds on these findings by investigating the role of allomorphy in early morphological acquisition. We tested whether infants relate novel words suffixed with [-z] and [-s] allomorphs of the -s suffix and their stems. We find that English-learning 6-month-olds relate novel words suffixed with the [-z], but not [-s], allomorph with stems, providing evidence for an acquisition trajectory where infants discover morphemes one allomorph at a time.

This study aimed to explore the effect of various feedback types on word learning in preschool children, with consideration of the word’s morpho-phonological structure. Sixty-three five-year-old children participated in three sessions of learning artificial words derived from pseudo-roots in Hebrew, with half constructed using established morpho-phonological patterns. Participants received either no feedback, verification feedback, corrective feedback, or verification plus corrective feedback. The training encompassed word identification and production. Accuracy and reaction time (RT) were measured. The results indicated that corrective feedback produced the highest accuracy and fastest RTs. Providing verification feedback led to improved performance compared to no feedback. While words with existing morpho-phonological patterns were learned more efficiently, the positive impact of corrective feedback remained consistent across both word types. These findings offer practical implications for optimizing word learning conditions, highlighting the importance of corrective feedback in word learning, and more broadly, aligning the feedback type to the learning task.

We present a simulation study based on a cognitive architecture that unifies various early language acquisition phenomena in laboratory and naturalistic settings. The model adaptively learns procedures through trial-and-error using general-purpose operators, guided by learned contextual associations to optimise future performance. For laboratory-based studies, simulated preferential focusing explains the delayed behavioural onset of statistical learning and the possible age-related decrease in algebraic processing. These findings suggest a link to continuous, implicit learning rather than explicit strategy acquisition. Moreover, procedures are not static but can evolve over time, and multiple plausible procedures may emerge for a given task. Besides, the same model provides a proof-of-concept for word-level phonological learning from naturalistic infant-directed speech, demonstrating how age-related processing efficiency may influence learning trajectories implicated in typical and atypical early language development. Furthermore, the artile discusses the broader implications for modelling other aspects of real-world language acquisition.

Children are known to derive more implicatures when the required alternative is made salient through contrast or when it is made contextually relevant through a story or a Question Under Discussion. We investigated the exclusivity implicature of three disjunctions (sau “or”, sau… sau, and fie…fie “either…or”) in child Romanian, an understudied language in the previous literature. Three experiments reveal that the mere presence of the stronger alternative, that is, simply hearing unrelated conjunctive statements in the course of the experiment, is not enough to boost implicatures. Rather, implicatures increase as a result of both access to alternatives and contextual relevance (expressed through conjunctive questions such as Did the hen push the train and the boat?). Interestingly, the boost in implicatures was observed only for sau-based disjunctions, not for fie…fie, which we conjecture may be due to children treating the latter as ambiguous between disjunction and conjunction.

The current study characterized voice onset time (VOT) and vowel onset fundamental frequency (F0) in the production of three Vietnamese alveolar stops (i.e. /t̪ʰ/, /t/, and /d/) by monolingual Vietnamese children and adults. Eighty Vietnamese children aged 3–7 years and 16 adults aged 22–44 years participated in this study. Unlike speakers of other languages with a three-way voicing contrast, Vietnamese children were able to produce distinct categories for the three Vietnamese stop categories by 3 years of age. However, differences in vowel onset F0 among the three voicing categories were not significant in any age group. These findings enhance our understanding of how Vietnamese children acquire three-way voicing contrast in stop production and offer broader insights into stop consonant acquisition across languages.

The present study examines whether presenting words in song versus spoken sentences can lead to differences in word learning in 47–50-month-old children. This work extends previous findings on this topic and evaluates whether the location of pitch changes within the song may contribute to how well the words are learned. Using a Preferential Looking Paradigm, 32 children were taught the names of objects, either in spoken sentences or in a song that followed an unfamiliar melody. In both conditions, the novel word was emphasized by a pitch change. Looking patterns indicated that children learned the names of the novel items better when the words were trained in the spoken sentence compared to the song condition. The findings are discussed in relation to theories of word learning, and how differences in the characteristics between speech and song may relate to variability in how well new words are acquired.

Recent evidence from cross-situational learning (CSL) studies have shown that adult learners can acquire words and grammar simultaneously when sentences of the novel language co-occur with dynamic scenes to which they refer. Syntactic bootstrapping accounts suggest that grammatical knowledge may help scaffold vocabulary acquisition by constraining possible meanings, thus, for children, words and grammar may be acquired at different rates. Twenty children (ages 8 to 9) were exposed in a CSSL study to an artificial language comprising nouns, verbs, and case markers occurring within a verb-final grammatical structure. Children acquired syntax (i.e., word order) effectively, but we found no evidence of vocabulary learning, whereas previous adult studies showed learning of both from similar input. Grammatical information may thus be available early for children, to help constrain and support later vocabulary learning. We propose that gradual maturation of declarative memory systems may result in more effective vocabulary learning in adults.

While a role of language in the development of Theory of Mind (ToM) is well established, the interplay with a child’s ability to understand structured scenarios remains unclear. A new scale (Pictorial Theory of Mind Scale), assessing true and false belief comprehension at different levels of linguistic complexity, was used to explore language effects on ToM while accounting for scenario comprehension. Thirty-nine children (aged 4–6 years; 53.8% female) participated in this study. Results showed that 46.8% of 4- to 6-year-olds can understand false beliefs from picture-based scenarios with limited language output. Both language and scenario comprehension contributed to ToM in first-order false beliefs, whereas only scenario comprehension predicted true beliefs. In contrast, only language predicted second-order false beliefs, highlighting their different roles in ToM development.

We present a new corpus of child and child-directed speech (CDS) in Palestinian Arabic. It includes transcriptions following the CHILDES guidelines and features recordings of 16 monolingual Palestinian Arabic-speaking children with an age range of 19–58 months and their adult interlocutors. We analyse the children’s morphosyntactic development and identify a variety of target word orders (45 in child speech, 50 in CDS), with prevalent SV(O) structures; we also found high rates of null subjects in both populations, marginal errors in children’s verbal agreement morphology, and early emergence of serial verb constructions, observed from 23 months of age.

This study assessed the association between home learning environment (HLE) at 3 years of age and children’s concurrent and longitudinal vocabulary skills. HLE consisted of the following activities done with primary caregivers: storytelling, drawing, music, toys and games, everyday home activities, playing outdoors, and reading. Results demonstrated that a higher HLE score at 3 years was concurrently related to higher expressive vocabulary and grammar scores, and longitudinally to higher receptive language scores from 5 to 9 years of age. Taken together, these findings suggest that children’s HLE represents a significant contributor to children’s concurrent and longitudinal language skills.

We present the typological approach to child language research. The typological approach places language diversity at the centre of acquisition research, thereby limiting arbitrary adjustments to theory and practice. We apply the typological approach to Ingram’s (2002) measures of whole-word phonological complexity (PMLU) and proximity (PWP). Our generalised PMLUg measure takes into account crosslinguistic variation in word status, including complex predicates and words without vowels. We analysed conversational data from Dutch, English, Japanese, Portuguese, Spanish, and Xi’iùy to determine whether two-year-old children target and produce words with significant between-language differences in phonological complexity. We found significant between-language differences in PMLUg for the target and produced words, but not PWPg. Comparing the complexity of the children’s words with the complexity of target words reveals their growth potentials along the syllable and consonant dimensions. Our study begins the cumulative investigation of the features that determine whole-word phonological complexity and proximity crosslinguistically.

We examined the direct and indirect associations between home literacy environment (HLE) and children’s listening comprehension and word reading in Chinese. Three hundred forty-seven Chinese kindergarten children (mean age = 74.01 months, 50% female) were tested on measures of pinyin letter knowledge, phonological awareness, vocabulary, word reading, and listening comprehension. Their parents completed a questionnaire about their socioeconomic status and the three aspects of HLE (code-related and meaning-related HLE, access to literacy resources). Results of path analysis showed that access to literacy resources was indirectly associated with both listening comprehension and word reading through the effects of phonological awareness and vocabulary. These findings suggest that in the early phases of language and literacy development, print materials in the home may be important not only for written-language skills but also for oral-language skills.

Sentences with a plural subject receive a distributive reading if the predicate refers to the atomic members, or a collective one if it relates to the whole group. Previous accounts suggest that the distributive representation includes an additional semantic operator, and comprehension experiments show that adults interpret an ambiguous sentence as collective. However, children accept distributive readings more frequently, questioning their presumed greater difficulty. The current study investigates these interpretations in a novel way through a production study, where Italian adults and preschoolers described distributive and collective pictures. Adults produced more distributive expressions, in line with semantic theories and psycholinguistic findings. Preschoolers, however, showed limited sensitivity to the need for disambiguating markers, showing in particular that knowledge of distributive quantifiers is not fully acquired by the age of five, at least in the production domain. We discuss our results at the intersection of language acquisition, semantic theories, and cognitive development.