Many studies have shown that morphological knowledge has effects on reading comprehension separate from other aspects of language knowledge. This has implications for reading instruction and assessment: it suggests that children could have reading comprehension difficulties that are due to a lack of morphological knowledge, and thus, that explicit instruction of morphology might be helpful for them, indeed for all children. To find children who might especially benefit from specific instruction in morphology, we would need good tests of morphological knowledge. We evaluated a set of morphological awareness assessments to determine whether they conclusively tapped into morphological knowledge, and found that it was not possible to be certain that they were accurately targeting morphological knowledge.

Vocabulary size is a crucial early indicator of language development, for both monolingual and bilingual children. Assessing vocabulary in bilingual children is complex because they learn words in two languages, and there remains significant controversy about how to best measure their vocabulary size, especially in relation to monolinguals. This study compared monolingual vocabulary with different metrics of bilingual vocabulary, including combining vocabulary across languages to count either the number of words or the number of concepts lexicalized and assessing vocabulary in a single language. Data were collected from parents of 743 infants and toddlers aged 8-33 months learning French and/or English, using the MacArthur-Bates Communicative Development Inventories. The results showed that the nature and magnitude of monolingual-bilingual differences depended on how bilinguals' vocabulary was measured. Compared with monolinguals, bilinguals had larger expressive and receptive word vocabularies, similarly sized receptive concept vocabularies and smaller expressive concept vocabularies. Bilinguals' single-language vocabularies were smaller than monolinguals' vocabularies. The study highlights the need to better understand the role of translation equivalents in bilingual vocabulary development and the potential developmental differences in receptive and expressive vocabularies.

Kidd and Garcia (2022) report that language acquisition studies are skewed towards monolingual and English-speaking populations. This commentary considers Kidd and Garcia's arguments in light of our research on mother-preschooler discourse and non-verbal communication in Thai monolingual and Thai-English bilingual children. We discuss lessons learned from testing linguistically diverse children and underscore the importance of research on non-WEIRD populations. We advocate for the inclusion of children who speak understudied languages and those who speak multiple languages in developmental science.

In this commentary on the article by Kidd and Garcia, we point out that research on natural signed languages is an important component of the goal of broadening the database of knowledge about how languages are acquired. While signed languages do display some modality effects, they also have many similarities to spoken languages, both in function and in form. Thus, research on signed languages and their acquisition is important for a fuller understanding of the diversity of languages. Since signed languages are often learned in contexts other than those of typical input, it is also important to document the effects of input variation; we also see it as critical that input be provided as early as possible from models as fluent as possible. Finally, we call for removing existing barriers to training and education for would-be researchers, especially those interested in working on signed languages. Importantly, we advocate for the recognition of signed languages, for signed language research, and for the empowerment of community members to lead this research.

This study is based on naturalistic speech samples produced by one child learning Cree as her first language (2;01-4;03) and presents the first investigation into the development of preverbs in the language. Preverbs are an optional class of morpheme which precede the lexical verb stem, dividing into grammatical, lexical and directional (deictic) subclasses. Of nine preverb types in the child's inventory, 47/48 tokens are grammatical. We argue that these appear early because they exhibit phonological transparency (do not alternate in form) and positional predictability (are restricted to preverb position). Lexical and directional preverbs, however, alternate in form and may appear in either preverb position or within the lexical stem. Furthermore, the child first began to use preverbs with the grammatically simpler independent (default) inflection (2;04), and 7 months later with the more syntactically restrictive conjunct inflection (2;11). She also used each preverb with one inflection type only, even where a choice of inflections was available, and she never produced more than one preverb per verb complex although multiple preverbs are common. In sum, grammatical complexity appears to be a driving factor in determining the child's development pattern.

Ambridge's proposal cannot account for the most basic observations about phonological patterns in human languages. Outside of the earliest stages of phonological production by toddlers, the phonological systems of speakers/learners exhibit internal behaviours that point to the representation and processing of inter-related units ranging in size from sub-segmental (featural) and segmental to larger prosodic units ranging from the syllable all the way to the phonological utterance. Only theories which embrace these units can make proper predictions about phonological behaviours.

Reading picture books to pre-literate children is associated with improved language outcomes, but the causal pathways of this relationship are not well understood. The present analyses focus on several syntactic differences between the text of children's picture books and typical child-directed speech, with the aim of understanding ways in which picture book text may systematically differ from typical child-directed speech. The analyses show that picture books contain more rare and complex sentence types, including passive sentences and sentences containing relative clauses, than does child-directed speech. These differences in the patterns of language contained in picture books and typical child-directed speech suggest that one important means by which picture book reading may come to be associated with improved language outcomes is by providing children with types of complex language that might be otherwise rare in their input.

Children with autism spectrum disorder (ASD) are prone to personal pronoun difficulties. This paper investigates maternal input as a potential contributing factor, focusing on an early developmental stage before ASD diagnosis. Using Quigley and McNally's (2013) corpus of maternal speech to infants (3-19 months; N = 19) who are either at high or low risk for a diagnosis of ASD (Quigley & McNally, 2013), we asked whether mothers used fewer pronouns with high-risk infants. Indeed, high-risk infants heard fewer second-person pronouns relative to their names than low-risk infants. We further investigated the contexts in which mothers were using infants' names. Our results indicated that mothers of high-risk infants often used the infants' names simply to get their attention by calling them. We suggest that high-risk infants may thus hear relatively fewer pronouns because their mothers spend more time trying to get their attention. This may be related to differences in social-communicative behavior between low-risk and high-risk infants.

Morphophonological processing involves the phonological analysis of morphemes. Item-specific phonological characteristics have been shown to influence morphophonological skills in children. This study investigates the relative contributions of broad phonological skills and vocabulary to production and judgement accuracies of the Dutch past tense and diminutive, two morphophonological processes. Typically developing children (age 5;0-10;0, = 114) were asked to produce and judge real and nonce diminutives and regular past tenses. Phonological processing skills were measured using a phonological awareness, digit span and nonword repetition task; vocabulary using the PPVT. Phonological skills and vocabulary contributed significantly to the production and judgement of the past tense and diminutive. The results underline the relation between phonological skills and the lexicon and the processing of morphophonology. These findings go further than showing the importance of the item-specific phonological context of the stem and suffix: they indicate that more general skills in the domain of phonology and vocabulary are involved.

This study investigates how children acquire prosodic focus-marking in Mandarin Chinese. Using a picture-matching game, we elicited spontaneous production of sentences in various focus conditions from children aged four to eleven. We found that Mandarin Chinese-speaking children use some pitch-related cues in some tones and duration in all tones in an adult-like way to distinguish focus from non-focus at the age of four to five. Their use of pitch-related cues is not yet fully adult-like in certain tones at the age of eleven. Further, they are adult-like in the use of duration in distinguishing narrow focus from broad focus at four or five but in not using pitch-related cues for this purpose at seven or eight. The later acquisition of pitch-related cues may be related to the use of pitch for lexical purposes, and the differences in the use of pitch in different tones can be explained by differences in how easy it is to vary pitch-related parameters without changing tonal identity.

The importance of input factors for bilingual children's vocabulary development was investigated. Forty-seven Argentine, 42 South Korean, 51 European American, 29 Latino immigrant, 26 Japanese immigrant, and 35 Korean immigrant mothers completed checklists of their 20-month-old children's productive vocabularies. Bilingual children's vocabulary sizes in each language separately were consistently smaller than their monolingual peers but only Latino bilingual children had smaller total vocabularies than monolingual children. Bilingual children's vocabulary sizes were similar to each other. Maternal acculturation predicted the amount of input in each language, which then predicted children's vocabulary size in each language. Maternal acculturation also predicted children's English-language vocabulary size directly.

This study examines whether children with specific language impairment (SLI) acquiring a language with a rich case marking system (Hungarian) have difficulty with case, and, if so, whether the difficulty is comparable for spatial and nonspatial meanings. Data were drawn from narrative samples and from a sentence repetition task. Suffixes were tested both in their spatial and nonspatial meanings. Participants with SLI were compared to same-age peers and younger typically developing children matched on receptive vocabulary scores ( VC children ). Results show that although case-marking errors are very rare in spontaneous speech in Hungarian children with SLI, the number of case marked nouns and of different case markers is significantly lower in children with SLI. In the elicited production task, overall performance of the children with SLI was significantly below that of VC children, but children with SLI and VC children scored higher with spatial than with nonspatial meanings. The results are in line with expectations based on processing accounts which posit greater difficulties with less transparent details of grammar.

This paper reports on the development and use of the Developmental Sentence Scoring for Japanese (DSSJ), a new morpho-syntactical measure for Japanese constructed after the model of the English Developmental Sentence Scoring model (Lee, 1974). Using this measure, we calculated DSSJ scores for 84 children divided into six age groups between 2;8 and 5;2 on the basis of 100-sentence samples collected from free-play child-adult conversations. The analysis showed a high correlation of the DSSJ overall score with the Mean Length of Utterance. The analysis of the DSSJ subarea scores revealed large variations between these subarea scores for children with similar overall DSSJ scores. When investigating the high-scoring children (over 1 over group average), most children scored high in three to five subareas, but the combination of scores for these subareas varied from child to child. It is concluded that DSSJ is a valuable tool especially for the language acquisition research. The overall DSSJ score reliably reflects the overall morpho-syntactic development of Japanese children, and the subarea scores provide specific information on individual acquisition patterns.

One of the most prominent issues in early cognitive and linguistic development concerns how children figure out meanings of words from hearing them in context, since in many contexts there are multiple words and multiple potential referents for those words. Recent findings concerning on-line sentence comprehension suggest that, within the conversational context, potential referents compete for mappings to words. Three experiments examined whether such competitive processes may play a role in young children's learning of novel adjectives in an artificial word learning task. According to a competitive process view, although young children often mismap adjectives to whole objects rather than the properties of objects, explicitly mentioned familiar words should strongly map to referents consistent with those words and thereby decrease the likelihood of novel words being mismapped to these referents. Experiments 1 and 2 examined the role of the mere mention of familiar words and the role of word order in two year olds' ability to map a novel adjective to a property. Experiment 3 examined these processes in three year olds. The results indicate that lexical competition plays a particularly strong role in helping two year olds map a novel object to a property, whereas syntactic information about form class may also be informative to older children. The results suggest how fundamental processes of lexical competition in on-line word comprehension may give young learners a way to leverage known words in learning new words.

The passive construction is acquired relatively late by children learning to speak many languages, with verbal passives not fully acquired until age 6 in English. In other languages it appears earlier, around age 3 or before. Use of passive construction in young children was examined in two Eastern Bantu languages spoken in Kenya (Kiswahili and Kigiriama), both with frequent use of passive. The passive was used productively very early (2;1) in these languages, regardless of the method used to measure productivity. In addition, non-actional passives, particularly rare in English and some other European languages, were seen at these early ages. The proportion of verbs that were passive varied between individuals, both in children's speech and in the input to children. Pragmatic and grammatical features of the passive in some languages have previously been suggested to drive early passive acquisition, but these features are not found consistently in the two languages studied here. Findings suggest that the relatively high frequency of input found in these languages is the most plausible reason for early productive use of the passive.

Children's ability to interpret color adjective noun phrases (e.g., red butterfly) as contrastive was examined in an eyetracking study with 6-year-old Russian children. Pitch accent placement (on the adjective , or on the noun ) was compared within a visual context containing two red referents (a butterfly and a fox) when only one of them had a contrast member (a purple butterfly) or when both had a contrast member (a purple butterfly and a grey fox). Contrastiveness was enhanced by the Russian-specific 'split constituent' construction (e.g., . . .) in which a contrastive interpretation of the color term requires pitch accent on the adjective, with the nonsplit sentences serving as control. Regardless of the experimental manipulations, children had to wait until hearing the noun (butterfly) to identify the referent, even in splits. This occurred even under conditions for which the prosody and the visual context allow adult listeners to infer the relevant contrast set and anticipate the referent prior to hearing the noun (accent on the adjective in 1-Contrast scenes). Pitch accent on the adjective did facilitate children's referential processing, but only for the nonsplit constituents. Moreover, visual contexts that encouraged the correct contrast set (1-Contrast) only facilitated referential processing after hearing the noun, even in splits. Further analyses showed that children can anticipate the reference like adults but only when the contrast set is made salient by the preceding supportive discourse, that is, when the inference about the intended contrast set is provided by the preceding utterance.

An important question in verb learning is how children extend new verbs to new situational contexts. In Study 1, 2 1/2-year-old children were shown a complex event followed by new events that preserved only the action from the initial event, only the result, or no new events. Children seeing events that preserved either the action or the result produced appropriate verb extensions at test while children without this information did not. In a follow-up study, children hearing new verbs produced more extensions than did children hearing nonlabeling speech. These studies suggest that attention to related events is helpful to young verb learners, perhaps because they structurally align these events (e.g., Gentner, 1983; 1989) during verb learning.

Many of the verbs that young children learn early have been characterized as 'light.' However, there is no agreed upon definition of 'lightness' and no useable metric that could be applied to a wide array of verbs. This article provides evidence for one metric by which the 'lightness' of early-learned verbs might be measured: the number of objects with which they are associated (in adult judgment) or co-occur (in speech to and by children). The results suggest that early-learned light verbs and heavy verbs differ in the breadth of the objects they are associated with: light verbs have weak associations with specific objects, whereas heavy verbs are strongly associated with specific objects. However, there is an indication that verbs have narrower associations to objects in speech to children. The methodological usefulness of this metric is discussed as are the implications of the patterns of distributions for children's learning of common verbs.

The aim of the present study was to investigate how young children reduce a yes bias, the tendency to answer 'yes' to yes-no questions. Specifically, we examined three possible factors: verbal ability, inhibitory control and theory of mind. Results revealed that verbal ability and inhibitory control were strongly associated with a yes bias even after controlling for age. Regression analyses revealed that these two factors significantly predicted a yes bias. Theory of mind was not significantly correlated with a yes bias. The results indicate that young children may have to inhibit a dominant 'yes' response when they are supposed to respond 'no'. The development of verbal skills may reduce young children's yes biases.

Italian children are immersed in a gesture-rich culture. Given the large gesture repertoire of Italian adults, young Italian children might be expected to develop a larger inventory of gestures than American children. If so, do these gestures impact the course of language learning? We examined gesture and speech production in Italian and US children between the onset of first words and the onset of two-word combinations. We found differences in the size of the gesture repertoires produced by the Italian vs. the American children, differences that were inversely related to the size of the children's spoken vocabularies. Despite these differences in gesture vocabulary, in both cultures we found that gesture + speech combinations reliably predicted the onset of two-word combinations, underscoring the robustness of gesture as a harbinger of linguistic development.

Children vary widely in how quickly their vocabularies grow. Can looking at early gesture use in children and parents help us predict this variability? We videotaped 53 English-speaking parent-child dyads in their homes during their daily activities for 90-minutes every four months between child age 14 and 34 months. At 42 months, children were given the Peabody Picture Vocabulary Test (PPVT). We found that child gesture use at 14 months was a significant predictor of vocabulary size at 42 months, above and beyond the effects of parent and child word use at 14 months. Parent gesture use at 14 months was not directly related to vocabulary development, but did relate to child gesture use at 14 months which, in turn, predicted child vocabulary. These relations hold even when background factors such as socio-economic status are controlled. The findings underscore the importance of examining early gesture when predicting child vocabulary development.