This paper engages longstanding questions regarding how children acquire morphology in polysynthetic languages. It examines the roles of frequency, perceptual salience, and semantic complexity for morphemes in the acquisition of Northern East Cree possessive inflection, where prefixes and suffixes interact to encode possessors. Two studies analyze naturalistic video recordings of one adult and two children. Study 1 describes the frequency, salience, and complexity of possessor-encoding morphemes in the input. Study 2 traces the acquisition of these morphemes in child speech. Results indicate the acquisition of possessor inflection involves a combination of factors whose influences shift over time. Perceptual salience plays a key role in early noun production, but frequency later corresponds more clearly to acquisitional order for high-frequency morphemes. Complexity is hard to isolate from frequency, although neither factor clearly determines acquisitional order for low-frequency morphemes. The paper concludes by considering implications for science and potential applications for Cree communities.

Children up to school age are known to have difficulty comprehending complex sentences with temporal connectives, but the reasons remain controversial. We tested six- to twelve-year-old children to assess how the iconicity of event-language mapping, type of connective, and clause order mediate the comprehension of temporal sentences. Sixty monolingual Greek-speaking children and 15 adult controls completed a picture-sequence selection task in which they judged after- and before-sentences in iconic and non-iconic order. Up to age twelve, children did not reach full adult-like comprehension of the connectives; performance in non-iconic after-sentences was significantly lower than in the other three conditions across all ages. We conclude that neither iconicity, connective, nor clause order can fully explain these findings and propose an account based on the interaction of iconicity and clause order: non-iconic, sentence-medial after requires revision of the initial event representation, resulting in an event-semantic kindergarten-path that children find difficult to overcome.

Metaphors are key to how children conceptualise the world around them and how they engage socially and educationally. This study investigated metaphor comprehension in typically developing Arabic-speaking children aged 3;01-6;07. Eighty-seven children were administered a newly developed task containing 20 narrated stories and were asked to point at pictures that best illustrated the metaphoric expression. The results were examined through a mixed ANCOVA, testing the effects of chronological age, metaphor type (primary, perceptual) and metaphor conventionality (conventional, novel) on metaphor comprehension. Children could understand some metaphors just after their third birthday, and their comprehension increased with age. Children’s performance was somewhat better on primary than perceptual, and much better on conventional than novel metaphors. These findings are discussed in light of conceptual metaphor theory (Lakoff & Johnson, 2008) and structure mapping theory (Gentner & Markman, 1997), confirming differences in the acquisition of different metaphor types.

Daily language interactions predict child outcomes. For multilingual families who rear neurodiverse children and who may be minoritized for their language use, a dearth of research examines families’ daily language interactions. Utilizing a language socialization framework and a case study methodology, 4,991 English and Spanish utterances from a 5-year old autistic child and his family were collected during naturally occurring interactions over 10 days. Utterances were analyzed for patterns of code-switching by speaker, activity setting, English or Spanish initial language, and code-switch function. Spanish was spoken in most activities. For reading, both languages were equally employed by the father. While participants used both languages across all activity settings, significant variations in code-switching type and function were observed by activity setting and speaker. We discuss implications for how home language resources can be integrated into autism interventions.

In gaining word knowledge, children’s semantic representations are initially imprecise before becoming gradually refined. We developed and tested a framework for a digital receptive vocabulary assessment that captured varied levels of representation as children learn words. At pre-test and post-test, children selected one of four images to match a word’s meaning: a correct target, a conceptually-related foil, a thematically-related foil, and a phonologically-similar foil. We expected that selecting a conceptually related foil would indicate that the word is understood at a deeper level than selecting a phonologically similar foil. Indeed, selection of phonological foils decreased from pre- to post-test, while selection of more advanced thematic and conceptual foils increased. These results demonstrate that this assessment tool probed semantic knowledge that might be characterized as intermediate word knowledge. The current paper presents a novel and sensitive way to capture the incremental process of word learning. Applications for vocabulary interventions are discussed.

Children’s early grammatical constructions, e.g., SVO, exhibit a learning curve with cumulative verb types (CVT) increasing exponentially. According to Ninio (2006), the fact that learning curves, though nonlinear, can be modelled by a continuous regression suggests instant generalisation. Moreover, differences in initial verbs across children indicate minimal involvement of semantics. This study tested these claims on the Spanish “se” constructions (SSCs) in two children, Juan and Lucía (Aguado-Orea & Pine, 2015). Ninio’s findings were replicated. Nonetheless, exploratory analyses indicated that curves are driven by the temporal distribution of tokens (instances of the SSC irrespective of verb type) and therefore may reflect non-productivity-related mechanisms, e.g., retrieval-based learning. Furthermore, hapax verbs were relatively late to emerge in the children’s data, suggesting emergent generalisation. Analyses of raw lexical frequencies indicated relative semantic homogeneity across the two children’s verb types, suggesting a semantic prototype. Nonetheless, ecological factors may also explain these lexical similarities.

This study explored monolingual and multilingual two- to five-year-olds’ reliance on a non-verbal and a verbal cue during word-referent mapping, in relation to vocabulary knowledge and, for the multilinguals, Dutch language exposure. Ninety monolingual and sixty-seven multilingual children performed a referential conflict experiment that pitted a non-verbal (pointing) cue and a verbal (mutual exclusivity) cue. Mixed-effect regressions showed no main effects of vocabulary and language exposure. An interaction between vocabulary and group showed that lower vocabulary scores were associated with a stronger reliance on pointing over mutual exclusivity for multilinguals (but not monolinguals). Furthermore, an interaction between vocabulary, language exposure, and cue word (novel vs. familiar label) indicated that multilinguals with lower exposure and lower vocabulary showed a stronger reliance on pointing over mutual exclusivity when a novel rather than familiar word was used. These findings suggest that multilingual and monolingual children go through different trajectories when learning to map words to referents.

Using both online and offline measures, this study investigates how maternal education and work status (stay-at-home, part-time, full-time) are jointly associated with infants’ word learning ability and vocabulary size. One hundred 24-month-old infants completed a lab-based mutual exclusivity task, which assesses infants’ novel word learning ability. Caregivers reported infants’ productive vocabulary size using the MCDIs. There was no evidence for an association between infants’ productive vocabulary size and maternal education, maternal work status, or their interaction. However, infants’ novel word learning ability was significantly related to both maternal factors and their interaction. The positive association between maternal education and word learning performance was attenuated for infants of part-time and full-time working mothers compared to infants with at home mothers. These findings suggest that using real-time measures with high task demand may better capture developmental differences in infants and expand our understanding of maternal factors contributing to early language development.

The process by which infants learn verbs through daily social interactions is not well-understood. This study investigated caregivers’ use of verbs, which have highly abstract meanings, during unscripted toy-play. We examined how verbs co-occurred with distributional and embodied factors including pronouns, caregivers’ manual actions, and infants’ locomotion, gaze, and object-touching. Object-action verbs were used significantly more often during caregiver-infant joint attention interactions. Movement and cognition verbs showed distinct co-occurrences with different contexts. Cognition and volition verbs were differentiated by pronouns. These findings provide evidence for how verb acquisition may be supported by the distributional and embodied contexts in caregiver-infant interactions.

Idioms play an important role in language; however, little research has examined idioms in children’s natural language settings. This study explored idioms usage in maternal talk during mother-child shared book reading and its relation to children’s vocabulary development. Thirty-three Chinese children in Norway (aged 3;0–5;5) and their mothers participated. We observed shared reading at the onset of the study and assessed children’s receptive and expressive vocabulary in Chinese three times across one year. Results demonstrated that mothers used an average of 1.8 idioms and explained one-third of the idioms. Maternal idiom usage was correlated with their talk amount and lexical diversity. Individual growth modeling revealed that the number of idioms mothers used predicted the growth of children’s receptive vocabulary in Chinese. We speculate that idiom usage could be an effective and understudied marker of parental linguistic sophistication. This study underscores the importance of idiom exposure in children’s language environment.

Children who receive cochlear implants develop spoken language on a protracted timescale. The home environment facilitates speech-language development, yet it is relatively unknown how the environment differs between children with cochlear implants and typical hearing. We matched eighteen preschoolers with implants (31-65 months) to two groups of children with typical hearing: by chronological age and hearing age. Each child completed a long-form, naturalistic audio recording of their home environment (appx. 16 hours/child; >730 hours of observation) to measure adult speech input, child vocal productivity, and caregiver-child interaction. Results showed that children with cochlear implants and typical hearing were exposed to and engaged in similar amounts of spoken language with caregivers. However, the home environment did not reflect developmental stages as closely for children with implants, or predict their speech outcomes as strongly. Home-based speech-language interventions should focus on the unique input-outcome relationships for this group of children with hearing loss.

We assess the feasibility of conducting web-based eye-tracking experiments with children using two methods of webcam-based eye-tracking: automatic gaze estimation with the WebGazer.js algorithm and hand annotation of gaze direction from recorded webcam videos. Experiment 1 directly compares the two methods in a visual-world language task with five to six year-old children. Experiment 2 more precisely investigates WebGazer.js’ spatiotemporal resolution with four to twelve year-old children in a visual-fixation task. We find that it is possible to conduct web-based eye-tracking experiments with children in both supervised (Experiment 1) and unsupervised (Experiment 2) settings – however, the webcam eye-tracking methods differ in their sensitivity and accuracy. Webcam video annotation is well-suited to detecting fine-grained looking effects relevant to child language researchers. In contrast, WebGazer.js gaze estimates appear noisier and less temporally precise. We discuss the advantages and disadvantages of each method and provide recommendations for researchers conducting child eye-tracking studies online.

Extensive research has shown that children’s early words are learned through sensorimotor experience. Thus, early-acquired words tend to have more concrete meanings. Abstract word meanings tend to be learned later but less is known about their acquisition. We collected meaning-specific concreteness ratings and examined their relationship with age-of-acquisition data from large-scale vocabulary testing with children in grade 2 to college age. Earlier-acquired meanings were rated as more concrete while later-acquired meanings as more abstract, particularly for words typically considered to be concrete. The results suggest that sensorimotor experiences are important to early-acquired word meanings, and other experiences (e.g., linguistic) are important to later-acquired meanings, consistent with a multi-representational view of lexical semantics.

Two major trends on children’s skills to comprehend metaphors have governed the literature on the subject: the literal stage hypothesis vs. the early birds hypothesis (Falkum, 2022). We aim to contribute to this debate by testing children’s capability to comprehend novel metaphors (‘X is a Y’) in Spanish with a child-friendly, picture selection task, while also tracking their gaze. Further, given recent findings on the development of metonymy comprehension suggesting a U-shaped developmental curve for this phenomenon (Köder & Falkum, 2020), we aimed to determine the shape of the developmental trajectory of novel metaphor comprehension, and to explore how both types of data (picture selection and gaze behavior) relate to each other. Our results suggest a linear developmental trajectory with 6-year-olds significantly succeeding in picture selection and consistently looking at the metaphorical target even after question onset.

Limited studies have examined demographic differences in children’s vocabulary in longitudinal samples, while there are questions regarding the duration, direction, and magnitude of these effects across development. In this longitudinal study, we included over 400 Dutch children. Caregivers filled out N-CDIs when children were 9–11 months (measuring word comprehension, word production, and gestures) and around 2–5 years of age (measuring word production). At 2–5 years, we also administered a receptive vocabulary task in the lab. We examined demographic effects on vocabulary size across infancy and toddlerhood. We found a disadvantage for males in infants’ gestures and toddlers’ vocabulary production. We found a negative effect of maternal education on infants’ caregiver-reported vocabulary, but a positive effect on toddlers’ lab-administered receptive vocabulary. Lastly, we found a negative effect of multilingualism – but only for the lab-administered task. Examining predictors in large, longitudinal samples ensures their robustness and generalisability across development.

This study investigated differences in adult-child language interactions when parents and their three-to-four-year old children engage in wordless book reading, text-and-picture book reading and a small-world toy play activity. Twenty-two parents recorded themselves completing each activity at home with their child. Parent input was compared across contexts, focusing on interactive and conceptual domains: use of open prompts, expansions or extensions of children’s utterances, and use of decontextualised (abstract) language. Use of linguistic expansions was greater during book reading than toy play. Parents used open questions and added contingent conceptual information more often when reading wordless books than in both other conditions. Findings suggest that wordless books may combine the benefits of open-endedness and linguistic content based around a narrative. Parents’ use of abstract language also varied by condition. This study extends understanding of the role of activity context in shaping children’s language learning environments.

We investigated older children’s (7–12 years) ability to comprehend before and after sentences. Results found that three factors that influence pre-school aged children’s learning of these words continues to influence older children’s comprehension. Specifically, children’s accuracy is improved when the events can be naturally (vs. arbitrarily) ordered; when the clauses in the sentence iconically match (vs. mismatch) the order of the events in the world; and when sentences use before (vs. after). The first two factors are argued to directly facilitate the building of mental models while the last one does so indirectly because of patterns of input usage.

This study compared a unidimensional model of vocabulary and a two-factor model comprising vocabulary breadth and depth in a second language (L2). A total of 167 Chinese Grade 4 and 5 primary school children (Meanage = 9.96 years old) learning English as an L2 participated in this study, and they were tested on four English vocabulary tests. Our results of confirmatory factor analyses indicate that vocabulary breadth and depth were not two distinct dimensions, and the unidimensional model was supported. Theoretical and practical implications were discussed.

In the current pre-registered study, we examined the associations between shared book reading, daily screen time, and vocabulary size in 1,442 12- and 24-month-old Norwegian infants. Our results demonstrate a positive association between shared reading and vocabulary in both age groups, and a negative association between screen time and vocabulary in 24-month-olds. Exploratory analyses revealed that the positive relationship between shared reading and expressive vocabulary in 12-month-olds was stronger in lower SES groups, suggesting that shared reading may act as a compensatory mechanism attenuating potentially impoverished learning environment and parent-infant interactions in low-SES families.

This research investigated the impact of the number of talkers with whom children engage in daily conversation on their language development. Two surveys were conducted in 2020, targeting two-year-olds growing up in Japanese monolingual families. Caregivers reported the number of talkers in three age groups and children’s productive vocabulary via questionnaires. The results demonstrated significant effects of variability in talkers in fifth grade or above in Study 1 (N = 50; male = 23; r = .372) and in adult talkers in Study 2 (N = 175; non-nursery going; male = 76; r = .184) on children’s vocabulary development, after controlling for language exposure time and demographic variables. Possible mediating factors are discussed. This research extends previous findings from immigrant bilingual children to monolingual speakers in Japan, suggesting the potential contribution of available talkers other than caregivers in conversational environments.