The key aim of this special issue is to make developmental theory proposals concrete enough to evaluate with empirical data. With this in mind, I discuss proposals from the “Universal Grammar + statistics” (UG+stats) perspective for learning several morphology and syntax phenomena. I briefly review why UG has traditionally been part of many developmental theories of language, as well as common statistical learning approaches that are part of UG+stats proposals. I then discuss each morphology or syntax phenomenon in turn, giving an overview of relevant UG+stats proposals for that phenomenon, specific predictions made by each proposal, and what we currently know about how those predictions hold up. I conclude by briefly discussing where we seem to be when it comes to how well UG+stats proposals help us understand the development of morphology and syntax knowledge.

Pierce et al. (2017) have proposed that variations in the timing, quality and quantity of language input during the earliest stages of development are related to variations in the development of phonological working memory and, in turn, to later language learning outcomes. To examine this hypothesis, three groups of children who are at-risk for language learning were examined: children with cochlear implants (CI), children with developmental language disorder (DLD), and internationally-adopted (IA) children, Comparison groups of typically-developing monolingual (MON) children and second language (L2) learners were also included. All groups were acquiring French as a first or second language and were matched on age, gender, and socioeconomic status, as well as other group-specific factors; they were between 5;0–7;3 years of age at time of testing. The CI and DLD groups scored significantly more poorly on the memory measures than the other groups; while the IA and L2 groups did not differ from one another. While the IA group performed more poorly than the MON group, there was no difference between the L2 and MON groups. We also found differential developmental relationships between phonological memory and language among the groups of interest in comparison to the typically-developing MON and L2 groups supporting the hypothesis that language experiences early in life are consequential for language development because of their effects on the development of phonological memory.

We analysed both structural and functional aspects of sentences containing the four adverbials “after”, “before”, “because”, and “if” in two dense corpora of parent-child interactions from two British English-acquiring children (2;00–4;07). In comparing mothers’ and children's usage we separate out the effects of frequency, cognitive complexity and pragmatics in explaining the course of acquisition of adverbial sentences. We also compare these usage patterns to stimuli used in a range of experimental studies and show how differences may account for some of the difficulties that children have shown in experiments. In addition, we report descriptive data on various aspects of adverbial sentences that have not yet been studied as a resource for future investigations.

Young children adopt an event-chaining strategy when storytelling, frequently linking clauses with and. The current study tested whether age-related changes in clause-initial and usage might index narrative structure development in the Eugene Children's Story Corpus (ECSC), which includes 180 structured spontaneous narratives elicited yearly for three years from 60 children, aged five to seven at study onset. The narratives were segmented into clauses to quantify clause-initial and usage. Adult judgments of narrative coherence and cohesiveness were elicited as measures of narrative structure. Mean length of utterance (MLU) and clause (MLC) were used as measures of language complexity. Results indicated developmental increases in all measures, but only and-connected dependent clause usage increased with cross-sectional and longitudinal age. Only MLC predicted the relative frequency of clause-initial and regardless of children's age. These results suggest children's frequent use of and to connect events reflects immature language; its association with flat narrative structure is likely epiphenomenal.

Associations have been observed between socioeconomic status (SES) and language outcomes from early childhood, but individual variability is high. Exposure to high levels of stress, often associated with low-SES status, might influence how parents and infants interact within the early language environment. Differences in these early language behaviors, and in early neurodevelopment, might underlie SES-based differences in language that emerge later on. Analysis of natural language samples from a predominantly low-/mid-income sample of mother-infant dyads, obtained using the Language Environment Analysis (LENA) system, found that maternal reports of exposure to stressful life events, and perceived stress, were negatively correlated with child vocalizations and conversational turns when infants were 6 and 12 months of age. Greater numbers of vocalizations and conversational turns were also associated with lower relative theta power and higher relative gamma power in 6- and 12-month baseline EEG – a pattern that might support subsequent language development.

Categorical induction abilities are robust in typically developing (TD) preschoolers, while children with Autism Spectrum Disorders (ASD) frequently perform inconsistently on tasks asking for the transference of traits from a known category member to a new example based on shared category membership. Here, TD five-year-olds and six-year-olds with ASD participated in a categorical induction task; the TD children performed significantly better and more consistently than the children with ASD. Concurrent verbal and nonverbal tests were not significant correlates; however, the TD children's shape bias performance at two years of age was significantly positively predictive of categorical induction performance at age five. The shape bias, the tendency to extend a novel label to other objects of the same shape during word learning, appears linked with categorical induction ability in TD children, suggesting a common underlying skill and consistent developmental trajectory. Word learning and categorical induction appear uncoupled in children with ASD.

Although previous research has indicated that five-year-olds can use acoustic cues to disambiguate compounds (N1 + N2) from lists (N1, N2) (e.g., ‘ice-cream’ vs. ‘ice, cream’) (Yoshida & Katz, 2004, 2006), their productions are not yet fully adult-like (Wells, Peppé & Goulandris, 2004). The goal of this study was to examine this issue in Australian English-speaking children, with a focus on their use of F0, word duration, and pauses. Twenty-four five-year-olds and 20 adults participated in an elicited production experiment. Like adults, children produced distinct F0 patterns for the two structures. They also used longer word durations and more pauses in lists compared to compounds, indicating the presence of a boundary in lists. However, unlike adults, they also inappropriately inserted more pauses within the compound, suggesting the presence of a boundary in compounds as well. The implications for understanding children's developing knowledge of how to map acoustic cues to prosodic structures are discussed.

Is noun dominance in early lexical acquisition a widespread or a language-specific phenomenon? Thirty Singaporean bilingual English–Mandarin learning toddlers and their mothers were observed in a mother-child play interaction. For both English and Mandarin, toddlers’ speech and reported vocabulary contained more nouns than verbs across book reading and toy playing. In contrast, their mothers’ speech contained more verbs than nouns in both English and Mandarin but differed depending on the context of the interaction. Although toddlers demonstrated a noun bias for both languages, the noun bias was more pronounced in English than in Mandarin. Together, these findings support early noun dominance as a widespread phenomenon in the lexical acquisition debate but also provide evidence that language specificity also plays a minor role in children's early lexical development.

Infants struggle to understand familiar words spoken in unfamiliar accents. Here, we examine whether accent exposure facilitates accent-specific adaptation. Two types of pre-exposure were examined: video-based (i.e., listening to pre-recorded stories; Experiment 1) and live interaction (reading books with an experimenter; Experiments 2 and 3). After video-based exposure, Canadian English-learning 15- to 18-month-olds failed to recognize familiar words spoken in an unfamiliar accent. However, after face-to-face interaction with a Mandarin-accented talker, infants showed enhanced recognition for words produced in Mandarin English compared to Australian English. Infants with live exposure to an Australian talker were not similarly facilitated, perhaps due to the lower vocabulary scores of the infants assigned to the Australian exposure condition. Thus, live exposure can facilitate accent adaptation, but this ability is fragile in young infants and is likely influenced by vocabulary size and the specific mapping between the speaker and the listener's phonological system.

The study of language acquisition has a long and contentious history: researchers disagree on what drives this process, the relevant data, and the interesting questions. Here, I outline the Starting Big approach to language learning, which emphasizes the role of multiword units in language, and of coarse-to-fine processes in learning. I outline core predictions and supporting evidence. In short, the approach argues that multiword units are integral building blocks in language; that such units can facilitate mastery of semantically opaque relations between words; and that adults rely on them less than children, which can explain (some of) their difficulty in learning a second language. The Starting Big approach is a theory of how children learn language, how language is represented, and how to explain differences between first and second language learning. I discuss the learning and processing models at the heart of the approach and their cross-linguistic implications.

Children's differing learning trajectories cross-linguistically have been at the forefront of gender acquisition research, often with conflicting results and conclusions. As a result, the source of children's different learning behaviors in gender acquisition has been unclear. I argue that children's gender acquisition is driven by the search for productive patterns. First, I provide corpus studies where the predictions of a learning model (Yang, 2016) are formulated. Second, I report the results of an elicited production task on Icelandic-speaking children (N = 26, ages 2;6-6;3 years) and adults (N = 18) that puts these predictions to test. The results suggest that Icelandic-speaking children and adults draw a categorical distinction between productive and unproductive suffixes in Icelandic gender assignment. I discuss the implications of these findings for morphological learning beyond gender acquisition.

Young Latino children of immigrants typically speak primarily Spanish at home and are exposed to varying amounts of English. As a result, they often enter school with a wide range of proficiencies in each language. The current study investigated family background, language use at home and early childhood settings as predictors of Spanish and English language proficiencies among Latino dual language children (N = 228). Findings demonstrated divergent sets of predictors were associated with either Spanish or English proficiencies at kindergarten and second grade. Sociocultural variables (parent origin, gender, home language use, home literacy practices, and language use in early childhood settings) predicted children's Spanish proficiency, while socioeconomic variables (poverty, and maternal and paternal education) predicted children's English proficiency, with little to no overlap in these predictions. These results suggest that different supports are required for proficiency in Spanish and in English, highlighting the importance of sociocultural and socioeconomic factors.

Our motivation was to examine how toddler (2;6) and adult speakers of American English prosodically realize information status categories. The aims were three-fold: 1) to analyze how adults phonologically make information status distinctions; 2) to examine how these same categories are signaled in toddlers’ spontaneous speech; and 3) to analyze the three primary acoustic correlates of prosody (F0, intensity, and duration). During a spontaneous speech task designed as an interactive game, a set of target nouns was elicited as one of three types (new, given, corrective). Results show that toddlers primarily used H* across information status categories, with secondary preferences for deaccenting given information and for using L+H* for corrective information. Only duration distinguished information status, and duration, average pitch, and intensity differentiated pitch accent types for both adults and children. Discussion includes how pitch accent selection and input play a role in guiding prosodic realizations of information status.

Several studies investigated preschoolers’ ability to compute scalar and ad-hoc implicatures, but only one compared children's performance with both kinds of implicature with the same task, a picture selection task. In Experiment 1 (N = 58, age: 4;2-6;0), we first show that the truth value judgment task, traditionally employed to investigate children's pragmatic ability, prompts a rate of pragmatic responses comparable to the picture selection task. In Experiment 2 (N = 141, age: 3;8-9;2) we used the picture selection task to compare scalar and ad-hoc implicatures and linked the ability to derive these implicatures to some cognitive and linguistic measures. We found that four- and five-year-olds children performed better on ad-hoc than on scalar implicatures. Furthermore, we found that morphosyntactic competence was associated with success in both kinds of implicatures, while performance on mental state reasoning was positively associated with success on scalar but not ad-hoc implicatures.

The validity of the Language ENvironment Analysis (LENA) System was evaluated for Dutch. 216 5-min samples (six samples per age per child) were selected from daylong recordings at 5, 10 and 14 months of age of native Dutch-speaking younger siblings of children with autism spectrum disorder (N = 6) and of typically developing children (N = 6). Two native Dutch-speaking coders counted the amount of adult words (AWC), child vocalisations (CVC) and conversational turns (CT). Consequently, correlations between LENA and human estimates were explored. Correlations were high for AWC at all ages (r = .73 to .81). Regarding CVC, estimates were moderately correlated at 5 months (r = .57) but the correlation decreased at 10 (r = .37) and 14 months (r = .14). Correlations for CT were low at all ages (r = .19 to .28). Lastly, correlations were not influenced by the risk status of the children.

Constructivist approaches to language acquisition predict that form-function mappings are derived from distributional patterns in the input, and their contextual embedding. This requires a detailed analysis of the input, and the integration of information from different contingencies. Regarding the acquisition of morphology, it is shown which types of information leads to the induction of (lexical) categories, and to paradigm building. Regarding the acquisition of word order, it is shown how languages with fixed or variable word order profit from stable syntactic hyperschemas, but require a more detailed analyses of the form-function contingencies to identify the underlying, more specific semantic, syntactic and morphological patterns. At a theoretical level, it is shown how findings from acquisition and processing converge into new linguistic theories that aim to account for regular as well as irregular phenomena in language.

Researchers agree that early literacy activities, like book sharing and parent-child play, are important for stimulating language development. We hypothesize that book sharing is most powerful because it elicits more interactive talk in young children than other activities. Parents of 43 infants (9–18 months) made two daylong audio recordings using the LENA system. We compared a typical day, with spontaneous occurring activities, with an instructed day when caregivers were prompted to do book reading and toy play. Book sharing resulted in a combination of more parent talk, child talk, and interactions than other language activities. Research context did not influence outcomes: no differences were found in language use between the spontaneous and the instructed activities. Overall it seems clear that even with infants shared reading is a strong unique stimulator of language use from parent and child.

The functions of acoustic-phonetic modifications in infant-directed speech (IDS) remain a question: do they specifically serve to facilitate language learning via enhanced phonemic contrasts (the hyperarticulation hypothesis) or primarily to improve communication via prosodic exaggeration (the prosodic hypothesis)? The study of lexical tones provides a unique opportunity to shed light on this, as lexical tones are phonemically contrastive, yet their primary cue, pitch, is also a prosodic cue. This study investigated Cantonese IDS and found increased intra-talker variation of lexical tones, which more likely posed a challenge to rather than facilitated phonetic learning. Although tonal space was expanded which could facilitate phonetic learning, its expansion was a function of overall intonational modifications. Similar findings were observed in speech to pets who should not benefit from larger phonemic distinction. We conclude that lexical-tone adjustments in IDS mainly serve to broadly enhance communication rather than specifically increase phonemic contrast for learners.

In this paper we consider the order of emergence of comprehension of wh-questions and polar-questions. We argue that considerations of complexity and input favour the earlier emergence of polar questions; on the other hand, if one assumes that question understanding emerges as a consequence of interactive learning this favours (certain) wh-questions, as well as a small subclass of polar questions. We offer corpus evidence from the Providence corpus that (a certain class of) wh-questions are in fact understood earlier than the polar-questions. We test this observation using elicitation studies on German and Chinese speaking children. Our results confirm the finding from the corpus study and are in line with an interactive learning perspective for the emergence of understanding of questions.

How do children learn to communicate, and what do they learn? Traditionally, most theories have taken an associative, compositional approach to these questions, supposing children acquire an inventory of form-meaning associations, and procedures for composing / decomposing them; into / from messages in production and comprehension. This paper presents an alternative account of human communication and its acquisition based on the systematic, discriminative approach embodied in psychological and computational models of learning, and formally described by communication theory. It describes how discriminative learning theory offers an alternative perspective on the way that systems of semantic cues are conditioned onto communicative codes, while information theory provides a very different view of the nature of the codes themselves. It shows how the distributional properties of languages satisfy the communicative requirements described in information theory, enabling language learners to align their expectations despite the vastly different levels of experience among language users, and to master communication systems far more abstract than linguistic intuitions traditionally assume. Topics reviewed include morphological development, the acquisition of verb argument structures, and the functions of linguistic systems that have proven to be stumbling blocks for compositional theories: grammatical gender and personal names.