Vocabulary checklists completed by caregivers are a common way of measuring children's vocabulary knowledge. We provide evidence from checklist data from 31 children with and without autism spectrum disorder. When asked to report twice about whether or not their child produces a particular word, caregivers are largely consistent in their responses, but where they are inconsistent, these inconsistencies affect verbs more than nouns. This difference holds both for caregivers of children with autism spectrum disorder and caregivers of typically-developing children. We suggest that caregivers may be less sure of their child's knowledge about verbs than nouns. This data converges with prior evidence comparing language samples of words children produce in a recorded interaction with checklist data, and it has implications for how researchers use checklist data in cases where the reliability of estimates of verb knowledge is critical.

Human languages, signed and spoken, can be characterized by the structural patterns they use to associate communicative with . One such pattern is paradigmatic morphology, where complex words are built from the systematic use of sub-lexical units. Here, we provide evidence of emergent paradigmatic morphology akin to number inflection in a communication system developed without input from a conventional language, . We study the communication systems of four deaf child homesigners (mean age 8;02). Although these idiosyncratic systems vary from one another, we nevertheless find that all four children use handshape and movement devices productively to express cardinal and non-cardinal number information, and that their number expressions are consistent in both form and meaning. Our study shows, for the first time, that all four homesigners not only incorporate number devices into representational devices used as predicates , but also into gestures functioning as nominals, including deictic gestures. In other words, the homesigners express number by systematically combining additive markers for number ( inflectional morphemes) with representational and deictic gestures ( bases). The creation of new, complex forms with predictable meanings across gesture types and linguistic functions constitutes evidence for an inflectional morphological in homesign and expands our understanding of the structural patterns of language that are, and are not, dependent on linguistic input.

When linguistic input contains inconsistent use of grammatical forms, children produce these forms more consistently, a process called '.' Deaf children learning American Sign Language from parents who are non-native users of the language regularize their parents' inconsistent usages (Singleton & Newport, 2004). In studies of artificial languages containing inconsistently used morphemes (Hudson Kam & Newport, 2005, 2009), children, but not adults, regularized these forms. However, little is known about the precise circumstances in which such regularization occurs. In three experiments we investigate how the type of input variation and the age of learners affects regularization. Overall our results suggest that while adults tend to reproduce the inconsistencies found in their input, young children introduce regularity: they learn varying forms whose occurrence is conditioned and systematic, but they alter inconsistent variation to be more regular. Older children perform more like adults, suggesting that regularization changes with maturation and cognitive capacities.

While semantic and syntactic properties of verb meaning can impact the success of verb learning at a single age, developmental changes in how these factors influence acquisition are largely unexplored. We ask whether the impact of syntactic and semantic properties on verb vocabulary development varies with age and language ability for toddlers aged 16 to 30 months in a large sample ( = 5520, = 821; = 4699, cutoff = 15th percentile) of vocabulary checklist data from the MacArthur- Bates Communicative Development Inventory (MBCDI). Verbs from the MBCDI were coded for their syntactic and semantic properties, including manner/result meanings, durative/punctual events, and syntactic complexity. Both late talkers and typically developing children were less likely to produce syntactically complex verbs at younger ages as compared to older ages. Group differences emerged for manner/result: Typically developing children were more likely to produce manner verbs at all ages, but late talkers were more likely to produce result verbs. Regardless of group, children who produced more manner versus result verbs also had larger verb vocabulary sizes overall. These results suggest that late talkers and typically developing toddlers differ in how they build their verb vocabularies.

Parent input during interaction with young children varies across languages and contexts with regard to the relative number of words from different lexical categories, particularly nouns and verbs. Previous work has focused on spoken language input. Little is known about the lexical composition of parent input in American Sign Language (ASL). We investigated parent input in ASL in a sample of deaf mothers interacting with their young deaf children (n = 7) in a free play setting. Children ranged in age from 21 to 39 months (M = 31 months). A 20-minute portion of each interaction was transcribed and coded for a range of linguistic features in maternal input including utterance length, sign types and tokens, proportion of nouns and verbs, and functions of points. We found evidence for a significant verb bias in maternal input; mothers produced more verb tokens and unique verb types than any other word class. Verbs were produced more than twice as often as nouns (36% vs 17% of all tokens) and appeared in a higher proportion of utterances than nouns (57% vs. 31% of all utterances). Points were frequent in the input, often serving as pronouns replacing common or proper nouns. Maternal noun and verb tokens increased in frequency with child age and vocabulary. These findings provide an initial step in understanding the lexical properties of maternal input during free play interactions in ASL.

Natural languages contain systematic relationships between verb meaning and verb argument structure. Artificial language learning studies typically remove those relationships and instead pair verb meanings randomly with structures. Adult participants in such studies can detect statistical regularities associated with words in these languages and their use of novel words will adhere to those statistical regularities. However, word use in natural languages is associated with more than distributional statistics. Using an artificial language learning paradigm, we asked how a relationship between verb meaning and sentence structure affected learning and structure generalization. Twenty-four English-speaking adults watched videos described in an artificial language with two possible sentence structures. Half of the participants (statistics-only condition) learned a language with no relationship between verb meaning and sentence structure. The other half (semantics condition) learned a language in which verb meaning predicted which structures a verb occurred in. Although all learners were able to comprehend the learned structures with novel verbs, participants in the semantics conditions made grammaticality judgments and productions with novel verbs that were more consistent with the target language than participants in the statistics-only condition. The availability of semantic cues to verb subcategory supports artificial language learning.

Socioeconomic status (SES)-related language gaps are known to widen throughout the course of the school years; however, not all children from lower SES homes perform worse than their higher SES peers on measures of language. The current study uses mediation and moderated mediation to examine how cognitive and language abilities (vocabulary, reading, phonological processing, working memory) account for individual differences in a children's ability to infer a novel word's meaning, a key component in word learning, in school-aged children from varying SES backgrounds. Vocabulary and reading comprehension mediated the relationship between SES and accuracy when inferring word meanings. The relationship between SES, vocabulary, and inferring word meaning was moderated by age, such that the influence of vocabulary on task performance was strongest in young children. The reading pathway did not interact with age effects, indicating reading is an important contributor to SES-related differences in how children infer a word's meaning throughout grade school. These findings highlight different paths by which children's trajectories for inferring word meanings may be impacted.

Much research in child speech development suggests that young children coarticulate more than adults. There are multiple, not mutually-exclusive, explanations for this pattern. For example, children may coarticulate more because they are limited by immature motor control. Or they may coarticulate more if they initially represent phonological segments in larger, more holistic units such as syllables or feet. We tested the importance of several different explanations for coarticulation in child speech by evaluating how four-year-olds' language experience, speech practice, and speech planning predicted their coarticulation between adjacent segments in real words and paired nonwords. Children with larger vocabularies coarticulated less, especially in real words, though there were no reliable coarticulatory differences between real words and nonwords after controlling for word duration. Children who vocalized more throughout a daylong audio recording also coarticulated less. Quantity of child vocalizations was more predictive of the degree of children's coarticulation than a measure of receptive language experience, adult word count. Overall, these results suggest strong roles for children's phonological representations and speech practice, as well as their immature fine motor control, for coarticulatory development.

Shin and Mill (2021) propose four steps children go through when learning . Although I applaud Shin and Miller's focus on morphosyntactic variation, their accrual of evidence is post hoc and selective. Fortunately, Shin and Miller recognize this and encourage tests of their ideas. In support of their work, I share data from children with and without DLD within AAE and SWE to promote these child profiles and dialectal varieties in future studies.

This study examined how toddler looking to a discourse referent is mediated by the information status of the referent and the pitch contour of the referring expression. Eighteen-month-olds saw a short discourse of three sets of images with the proportion of looking time to a target analyzed during the final image. At test, the information status of the referent was either or and the referring expression was presented with one of three pitch contours (, (~H*), or (~L+H*)). In Experiment 1, toddlers looked reliably longer to a target referent when it was either to the discourse or carried a non-flat pitch contour. In Experiment 2, the referring expression was removed to observe effects of information status alone on looking to a target referent. Toddlers looked significantly longer to a target when it was versus . More fine-grained time course analyses of eye movements revealed differences in the speed and duration of fixation to a target. Overall, the experiments show that discourse reference in toddlers is mediated by the presence of newness and pitch contours, even in the case of information.

The current study investigated whether the difficulty in finding group differences in prosody between speakers with autism spectrum disorder (ASD) and neurotypical (NT) speakers might be explained by identifying different acoustic profiles of speakers which, while still perceived as atypical, might be characterized by different acoustic qualities. We modelled the speech from a selection of speakers (N = 26), with and without ASD, as a network of nodes defined by acoustic features. We used a community-detection algorithm to identify clusters of speakers who were acoustically similar and compared these clusters with atypicality ratings by naïve and expert human raters. Results identified three clusters: one primarily composed of speakers with ASD, one of mostly NT speakers, and one comprised of an even mixture of ASD and NT speakers. The human raters were highly reliable at distinguishing speakers with and without ASD, regardless of which cluster the speaker was in. These results suggest that community-detection methods using a network approach may complement commonly-employed human ratings to improve our understanding of the intonation profiles in ASD.

To learn new words, particularly verbs, child learners have been shown to benefit from the linguistic contexts in which the words appear. However, cross-linguistic differences affect how this process unfolds. One previous study found that children's abilities to learn a new verb differed across Korean and English as a function of the sentence in which the verb occurred (Arunachalam et al., 2013). The authors hypothesized that the properties of word order and argument drop, which vary systematically in these two languages, were driving the differences. In the current study, we pursued this finding to ask if the difference persists later in development, or if children acquiring different languages come to appear more similar as their linguistic knowledge and learning capacities increase. Preschool-aged monolingual English learners (N = 80) and monolingual Korean learners (N = 64) were presented with novel verbs in contexts that varied in word order and argument drop and accompanying visual stimuli. We assessed their learning by measuring accuracy in a forced-choice pointing task, and we measured eye gaze during the learning phase as an indicator of the processes by which they mapped the novel verbs to meaning. Unlike previous studies which identified differences between English and Korean learning 2-year-olds in a similar task, our results revealed similarities between the two language groups with these older preschoolers. We interpret our results as evidence that over the course of early childhood, children become adept at learning from a larger variety of contexts, such that differences between learners of different languages are attenuated.

The lack of diversity in the language sciences has increasingly been criticized as it holds the potential for producing flawed theories. Research on (i) geographically diverse language communities and (ii) on sign languages is necessary to corroborate, sharpen, and extend existing theories. This study contributes a case study of adapting a well-established paradigm to study the acquisition of sign phonology in Kata Kolok, a sign language of rural Bali, Indonesia. We conducted an experiment modeled after the familiarization paradigm with child signers of Kata Kolok. Traditional analyses of looking time did not yield significant differences between signing and non-signing children. Yet, additional behavioral analyses (attention, eye contact, hand behavior) suggest that children who are signers and those who are non-signers, as well as those who are hearing and those who are deaf, interact differently with the task. This study suggests limitations of the paradigm due to the ecology of sign languages and the sociocultural characteristics of the sample, calling for a mixed-methods approach. Ultimately, this paper aims to elucidate the diversity of adaptations necessary for experimental design, procedure, and analysis, and to offer a critical reflection on the contribution of similar efforts and the diversification of the field.

Language comprehension involves cognitive abilities that are specific to language as well as cognitive abilities that are more general and involved in a wide range of behaviors. One set of domain-general abilities that support language comprehension are executive functions (EFs), also known as cognitive control. A diverse body of research has demonstrated that EFs support language comprehension when there is conflict between competing, incompatible interpretations of temporarily ambiguous words or phrases. By engaging EFs, children and adults are able to select or bias their attention towards the correct interpretation. However, the degree to which language processing engages EFs in the absence of ambiguity is poorly understood. In the current experiment, we tested whether EFs may be engaged when comprehending speech that does not elicit conflicting interpretations. Different components of EFs were measured using several behavioral tasks and language comprehension was measured using an eye-tracking procedure. Five-year-old children (n=56) saw pictures of familiar objects and heard sentences identifying the objects using either their names or colors. After a series of objects were identified using one dimension, children were significantly less accurate in fixating target objects that were identified using a second dimension. Further results reveal that this decrease in accuracy does not occur because children struggle to shift between dimensions, but rather because they are unable to predict which dimension will be used. These effects of predictability are related to individual differences in children's EFs. Taken together, these findings suggest that EFs may be more broadly involved when children comprehend language, even in instances that do not require conflict resolution.

Multiple studies have reported mathematics underachievement for students who are deaf, but the onset, scope, and causes of this phenomenon remain understudied. Early language deprivation might be one factor influencing the acquisition of numbers. In this study, we investigated a basic and fundamental mathematical skill, automatic magnitude processing, in two formats (Arabic digits and American Sign Language number signs) and the influence of age of first language exposure on both formats by using two versions of the Number Stroop Test. We compared the performance of individuals born deaf who experienced early language deprivation to that of individuals born deaf who experienced sign language in early life and hearing second language learners of ASL. In both formats of magnitude representation, late first language learners demonstrated overall slower reaction times. They were also less accurate on incongruent trials but performed no differently from early signers and second language learners on other trials. When magnitude was represented by Arabic digits, late first language learners exhibited robust Number Stroop Effects, suggesting automatic magnitude processing, but they also demonstrated a large speed difference between size and number judgments not observed in the other groups. In a task with ASL number signs, the Number Stroop Effect was not found in any group, suggesting that magnitude representation might be format-specific, in line with the results from several other languages. Late first language learners also demonstrate unusual patterns of slower reaction time for neutral rather than incongruent stimuli. Together, the results show that early language deprivation affects the ability to automatically judge quantities expressed both linguistically and by Arabic digits, but that it can be acquired later in life when language is available. Contrary to previous studies that find differences in speed of number processing between deaf and hearing participants, we find that when language is acquired early in life, deaf signers perform identically to hearing participants.

The current study examined the effect of speaker variability on children's cross-situational word learning (XSWL). The study also examined the role of bilingual experience and sustained attention. Forty English monolingual children and 40 Spanish-English bilingual children ages 4-7 completed a XSWL task in a Single Speaker Condition and a Multiple Speaker Condition. Results indicated that speaker variability neither facilitated nor hindered XSWL. While monolingual children outperformed bilingual children, speaker-variability effects did not fluctuate across the two language groups. Notably, exposure to multiple speakers facilitated XSWL in children with poorer sustained attention skills, suggesting that variability in the input may be especially useful to children with poorer cognitive processing abilities.

Children's ability to learn words with multiple meanings may be hindered by their adherence to a one-to-one form-to-meaning mapping bias. Previous research on children's learning of a novel meaning for a familiar word (sometimes called a ) has yielded mixed results, suggesting a range of factors that may impact when children entertain a new meaning for a familiar word. One such factor is repetition of the new meaning (Storkel & Maekawa, 2005) and another is the acoustic differentiation of the two meanings (Conwell, 2017). This study asked 72 4-year-old English-learning children to assign novel meanings to familiar words and manipulated how many times they heard the words with their new referents as well as whether the productions were acoustically longer than typical productions of the words. Repetition supported the learning of a pseudohomophone, but acoustic differentiation did not.

Despite the seemingly simple mapping between adjectives and perceptual properties (e.g., color, texture), preschool children have difficulty establishing the appropriate extension of novel adjectives. When children hear a novel adjective applied to an individual object, they successfully extend the adjective to other members of the same object category but have difficulty extending it more broadly to members of different categories. We propose that the source of this difficulty lies at the interface of the linguistic and conceptual systems: children initially limit the extension of an adjective to the category of the object on which it was introduced. To test this hypothesis, we manipulated whether participants construed images as "pictures of things" (objects) or "blobs of stuff" (non-objects). For both 36-month-old children (Experiments 1 and 2) and adults (Experiment 3), the conceptual status of an image influenced how they extended an adjective applied to that image. Children extended novel adjectives more successfully when they construed the images as non-objects than when they construed the same images as objects. Similarly, adults were faster to make adjective extensions when construing the images as non-objects rather than objects. Learners of all ages must navigate this linguistic-conceptual interface in assessing whether and how novel adjectives should be extended to new individuals.

Maternal scaffolding and four-year-old children's linguistic skills were examined during toy play. Participants were 21 American-English monolingual and 21 Thai monolingual mother-child dyads. Results revealed cross-cultural differences in conversation styles between the two groups. American dyads adopted a high-elaborative style relative to Thai dyads. American and Thai mothers utilized unique sets of elicitation strategies to facilitate different aspects of children's language development, specifically American mothers focused on children's narrative skills whereas Thai mothers emphasized vocabulary learning. The two groups of children showed distinct patterns of conversation, for example American children produced greater evaluative statements whereas Thai children repeated their mothers' utterances more, which aligned with socialization goals of each respective culture. Mother-child narrative styles also differed as a function of child gender. Additionally, significant positive correlations were observed between maternal and child linguistic measures. These findings provide evidence for cross-cultural variation in communicative styles and toy play practices of American and Thai mother-child dyads, which reflect the social norms of individualistic and collectivist cultures. More broadly, the present study suggests that dyadic engagement during play is important for children's development and socialization, as maternal speech transfers knowledge of culture-specific pragmatic rules that the children learn to apply in social interactions.

Linguistic contexts provide useful information about verb meanings by narrowing the space of candidate concepts. Intuitively, the more information, the better. For example, "the tall girl is ing," as compared to "the girl is ing," provides more information about which event, out of multiple candidate events, is being labeled; thus, we may expect it to better facilitate verb learning. However, we find evidence to the contrary: in a verb learning study, preschoolers (N = 60, mean age = 38 months) only performed above chance when the subject was an unmodified determiner phase, but not when it was modified (Experiment 1). Experiment 2 replicated this pattern with a different set of stimuli and a wider age range (N = 60, mean age = 45 months). Further, in Experiment 2, we looked at both learning outcomes--by evaluating pointing responses at Test, and also the learning process--by tracking eye gaze during Familiarization. The results suggest that children's limited processing abilities are to blame for poor learning outcomes, but that a nuanced understanding of how processing affects learning is required.

Joint Attention (JA) and Supported Joint Engagement (Supported JE) have each been reported to predict later language development in typically developing (TD) children and children with Autism Spectrum Disorder (ASD). In this longitudinal study including 33 TD children (20 months at V1) and 30 children with ASD (33 months at V1), the contributions of JA and Supported JE to later language, assessed via standardized tests and spontaneous speech, were directly compared. Frequency and durations of JA and Supported JE episodes were coded from 30-minute interactions with caregivers; subsequent language skills were assessed two years later. JA duration in the ASD group significantly predicted later standardized and spontaneous language, most strongly in the low-verbal ASD subgroup. Supported JE measures did not positively predict later language in either group. These findings suggest that JA played a larger role with children with ASD with low-verbal abilities, but not with children with ASD with high-verbal abilities nor with the TD children. The current study adds to existing literature by providing further support for studying children with ASD as two subgroups based on their verbal abilities (high vs low), as well as directly comparing the effects of JA and Supported JE on later language development in such groups. Implications for further research are discussed.