Publications

Abstract

Introduction

Children's early language and communication skills are efficiently measured using parent report, for example, communicative development inventories (CDIs). These have scalable potential to determine risk of later language delay, and associations between delay and risk factors such as prematurity and poverty. However, there may be measurement difficulties in parent reports, including anomalous directions of association between child age/socioeconomic status and reported language. Findings vary on whether parents may report older infants as having smaller vocabularies than younger infants, for example.

Methods

We analysed data from the UK Communicative Development Inventory (Words and Gestures); UK-CDI (W&G) to determine whether anomalous associations would be replicated in this population, and/or with gesture. In total 1204 families of children aged 8–18 months (598 girls, matched to UK population for income, parental education and ethnicity as far as possible) completed Vocabulary and Gesture scales of the UK-CDI (W&G).

Results

Overall scores on the Gesture scale showed more significant relationships with biological risk factors including prematurity than did Vocabulary scores. Gesture also showed more straightforward relationships with social risk factors including income. Relationships between vocabulary and social risk factors were less straightforward; some at-risk groups reported higher vocabulary scores than other groups.

Discussion

We conclude that vocabulary report may be less accurate than gesture for this age. Parents have greater knowledge of language than gesture milestones, hence may report expectations for vocabulary, not observed vocabulary. We also conclude that gesture should be included in early language scales partly because of its greater, more straightforward association with many risk factors for language delay.

Abstract

A long-standing question in language development concerns the nature of the relationship between early lexical and grammatical knowledge. The very strong correlation between the two has led some to argue that lexical and grammatical knowledge may be inseparable, consistent with psycholinguistic theories that eschew a distinction between the two systems. However, little research has explicitly examined whether early lexical and grammatical knowledge are statistically separable. Moreover, there are two under-appreciated methodological challenges in such research. First, the relationship between lexical and grammatical knowledge may change during development. Second, non-linear mappings between true and observed scores on scales of lexical and grammatical knowledge could lead to spurious multidimensionality. In the present study, we overcome these challenges by using vocabulary and grammar data from several developmental time points and a statistical method robust to such non-linear mappings. In Study 1, we examined item-level vocabulary and grammar data from two American English samples from a large online repository of data from studies employing a commonly used language development scale. We found clear evidence that vocabulary and grammar were separable by two years of age. In Study 2, we combined data from two longitudinal studies of language acquisition that used the same scale (at 18/19, 21, 24 and 30 months) and found evidence that vocabulary and grammar were, under some conditions, separable by 18 months. Results indicate that, while there is clearly a very strong relationship between vocabulary and grammar knowledge in early language development, the two are separable. Implications for the mechanisms underlying language development are discussed.

Abstract

Preschoolers’ exposure to abstract language (i.e. talk beyond the here and now) during shared reading is associated with language development. This randomized intervention study tested whether preschoolers’ repeated exposure to simple and complex stories (as defined by the inferential demands of the story), and the extratextual talk associated with such stories, would lead to differences in language production during shared reading and to differential gains in vocabulary and narrative skills post intervention. An experimenter read scripted stories to 34 children (3;07–4;11) assigned to one of two story conditions (simple or complex) in small-groups, twice weekly over six weeks. Results showed that children in the complex story condition produced more complex language (as indexed by their mean length of utterance, use of mental and communication verbs, and use of subordinate clauses). However, post-intervention, children’s vocabulary and narrative skills did not differ between conditions. Specific kinds of stories and corresponding extratextual talk by adults may not only increase children’s exposure to rich and challenging input from the extratextual talk, but can also provide valuable opportunities for children to produce complex language. Theoretical and methodological implications are also discussed.

Abstract

While there are well-known demonstrations that children can use distributional information to acquire multiple components of language, the underpinnings of these achievements are unclear. In the current paper, we investigate the potential pre-requisites for a distributional learning model that can explain how children learn their first words. We review existing literature and then present the results of a series of computational simulations with Vector Space Models, a type of distributional semantic model used in Computational Linguistics, which we evaluate against vocabulary acquisition data from children. We focus on nouns and verbs, and we find that: (i) a model with flexibility to adjust for the frequency of events provides a better fit to the human data, (ii) the influence of context words is very local, especially for nouns, and (iii) words that share more contexts with other words are harder to learn.

Abstract

Language is a universal human ability, acquired readily by young children, whootherwise struggle with many basics of survival. And yet, language ability is variableacross individuals. Naturalistic and experimental observations suggest that children’slinguistic skills vary with factors like socioeconomic status and children’s gender.But which factors really influence children’s day-to-day language use? Here, weleverage speech technology in a big-data approach to report on a unique cross-culturaland diverse data set: >2,500 d-long, child-centered audio-recordings of 1,001 2- to48-mo-olds from 12 countries spanning six continents across urban, farmer-forager,and subsistence-farming contexts. As expected, age and language-relevant clinical risksand diagnoses predicted how much speech (and speech-like vocalization) childrenproduced. Critically, so too did adult talk in children’s environments: Children whoheard more talk from adults produced more speech. In contrast to previous conclusionsbased on more limited sampling methods and a different set of language proxies,socioeconomic status (operationalized as maternal education) was not significantlyassociated with children’s productions over the first 4 y of life, and neither weregender or multilingualism. These findings from large-scale naturalistic data advanceour understanding of which factors are robust predictors of variability in the speechbehaviors of young learners in a wide range of everyday contexts

Abstract

Eye gaze is a powerful ostensive cue in infant-caregiver interactions, with demonstrable effects on language acquisition. While the link between gaze following and later vocabulary is well-established, the effects of eye gaze on other aspects of language, such as speech processing, are less clear. In this EEG study, we examined the effects of the speaker’s eye gaze on ten-month-old infants’ neural tracking of naturalistic audiovisual speech, a marker for successful speech processing. Infants watched videos of a speaker telling stories, addressing the infant with direct or averted eye gaze. We assessed infants’ speech-brain coherence at stress (1–1.75 Hz) and syllable (2.5–3.5 Hz) rates, tested for differences in attention by comparing looking times and EEG theta power in the two conditions, and investigated whether neural tracking predicts later vocabulary. Our results showed that infants’ brains tracked the speech rhythm both at the stress and syllable rates, and that infants’ neural tracking at the syllable rate predicted later vocabulary. However, speech-brain coherence did not significantly differ between direct and averted gaze conditions and infants did not show greater attention to direct gaze. Overall, our results suggest significant neural tracking at ten months, related to vocabulary development, but not modulated by speaker’s gaze.

Abstract

At the group level, children exposed to certain health and demographic risk factors, and who have delayed language in early childhood are, more likely to have language problems later in childhood. However, it is unclear whether we can use these risk factors to predict whether an individual child is likely to develop problems with language (e.g., be diagnosed with a developmental language disorder). We tested this in a sample of 146 children who took part in the UK-CDI norming project. When the children were 15–18 months old, 1,210 British parents completed: (a) the UK-CDI (a detailed assessment of vocabulary and gesture use) and (b) the Family Questionnaire (questions about health and demographic risk factors). When the children were between 4 and 6  years, 146 of the same parents completed a short questionnaire that assessed (a) whether children had been diagnosed with a disability that was likely to affect language proficiency (e.g., developmental disability, language disorder, hearing impairment), but (b) also yielded a broader measure: whether the child’s language had raised any concern, either by a parent or professional. Discriminant function analyses were used to assess whether we could use different combinations of 10 risk factors, together with early vocabulary and gesture scores, to identify children (a) who had developed a language-related disability by the age of 4–6 years (20 children, 13.70% of the sample) or (b) for whom concern about language had been expressed (49 children; 33.56%). The overall accuracy of the models, and the specificity scores were high, indicating that the measures correctly identified those children without a language-related disability and whose language was not of concern. However, sensitivity scores were low, indicating that the models could not identify those children who were diagnosed with a language-related disability or whose language was of concern. Several exploratory analyses were carried out to analyse these results further. Overall, the results suggest that it is difficult to use parent reports of early risk factors and language in the first 2 years of life to predict which children are likely to be diagnosed with a language-related disability. Possible reasons for this are discussed.

Abstract

The present study investigates the developmental trajectory of abstract representations for syntactic structures in children. In a structural priming experiment on the dative alternation in German, we primed children from three different age groups (3–4 years, 5–6 years, 7–8 years) and adults with double object datives (Dora sent Boots the rabbit) or prepositional object datives (Dora sent the rabbit to Boots). Importantly, the prepositional object structure in German is dispreferred and only rarely encountered by young children. While immediate as well as cumulative structural priming effects occurred across all age groups, these effects were strongest in the 3- to 4-year-old group and gradually decreased with increasing age. These results suggest that representations in young children are less stable than in adults and, therefore, more susceptible to adaptation both immediately and across time, presumably due to stronger surprisal. Lexical boost effects, in contrast, were not present in 3- to 4-year-olds but gradually emerged with increasing age, possibly due to limited working-memory capacity in the younger child groups.

Abstract

There is a wealth of evidence demonstrating that executive function (EF) abilities are positively associated with language development during the preschool years, such that children with good executive functions also have larger vocabularies. However, why this is the case remains to be discovered. In this study, we focused on the hypothesis that sentence processing abilities mediate the association between EF skills and receptive vocabulary knowledge, in that the speed of language acquisition is at least partially dependent on a child’s processing ability, which is itself dependent on executive control. We tested this hypothesis in longitudinal data from a cohort of 3- and 4-year-old children at three age points (37, 43, and 49 months). We found evidence, consistent with previous research, for a significant association between three EF skills (cognitive flexibility, working memory [as measured by the Backward Digit Span], and inhibition) and receptive vocabulary knowledge across this age range. However, only one of the tested sentence processing abilities (the ability to maintain multiple possible referents in mind) significantly mediated this relationship and only for one of the tested EFs (inhibition). The results suggest that children who are better able to inhibit incorrect responses are also better able to maintain multiple possible referents in mind while a sentence unfolds, a sophisticated sentence processing ability that may facilitate vocabulary learning from complex input.

Abstract

For shared book reading to be effective for language development, the adult and child need to be highly engaged. The current paper adopted a mixed-methods approach to investigate caregiver’s language-boosting behaviours and children’s engagement during shared book reading. The results revealed there were more instances of joint attention and caregiver’s use of prompts during moments of higher engagement. However, instances of most language-boosting behaviours were similar across episodes of higher and lower engagement. Qualitative analysis assessing the link between children’s engagement and caregiver’s use of speech acts, revealed that speech acts do seem to contribute to high engagement, in combination with other aspects of the interaction.

Abstract

We investigated whether learning an artificial language at 17 months was predictive of children’s natural language vocabulary and grammar skills at 54 months. Children at 17 months listened to an artificial language containing non-adjacent dependencies, and were then tested on their learning to segment and to generalise the structure of the language. At 54 months, children were then tested on a range of standardised natural language tasks that assessed receptive and expressive vocabulary and grammar. A structural equation model demonstrated that learning the artificial language generalisation at 17 months predicted language abilities – a composite of vocabulary and grammar skills – at 54 months, whereas artificial language segmentation at 17 months did not predict language abilities at this age. Artificial language learning tasks – especially those that probe grammar learning – provide a valuable tool for uncovering the mechanisms driving children’s early language development.

Abstract

Caregiver abstract talk during shared reading predicts preschool-age children’s vocabulary development. However, previous research has focused on level of abstraction with less consideration of the style of extratextual talk. Here, we investigated the relation between these two dimensions of extratextual talk, and their contributions to variance in children’s vocabulary skills. Caregiver level of abstraction was associated with an interactive reading style. Controlling for socioeconomic status and child age, high interactivity predicted children’s concurrent vocabulary skills whereas abstraction did not. Controlling for earlier vocabulary skills, neither dimension of the extratextual talk predicted later vocabulary. Theoretical and practical relevance are discussed.

Abstract

Children’s ability to share attention with another social partner (i.e., joint attention) has been found to support language development. Despite the large amount of research examining the effects of joint attention on language in hearing population, little is known about how deaf children learning sign languages achieve joint attention with their caregivers during natural social interaction and how caregivers provide and scaffold learning opportunities for their children. The present study investigates the properties and timing of joint attention surrounding familiar and novel naming events and their relationship to children’s vocabulary. Naturalistic play sessions of caretaker-child-dyads using American Sign Language were analyzed in regards to naming events of either familiar or novel object labeling events and the surrounding joint attention events. We observed that most naming events took place in the context of a successful joint attention event and that sign familiarity was related to the timing of naming events within the joint attention events. Our results suggest that caregivers are highly sensitive to their child’s visual attention in interactions and modulate joint attention differently in the context of naming events of familiar vs. novel object labels.

Abstract

Observational and checklist measures of vocabulary composition have both recently been used to look at the absolute proportion of nouns in children's early vocabularies. However, they have tended to generate rather different results. The present study is an attempt to investigate the relationship between such measures in a sample of 26 children between 1;1 and 2;1 at approximately 50 and 100 words. The results show that although observational and checklist measures are significantly correlated, there are also systematic quantitative differences between them which seem to reflect a combination of checklist, maternal-report and observational sampling biases. This suggests that, although both kinds of measure may represent good indices of differences in vocabulary size and composition across children and hence be useful as dependent variables in correlational research, neither may be ideal for estimating the absolute proportion of nouns in children's vocabularies. The implication is that questions which rely on information about the absolute proportion of particular kinds of words in children's vocabularies can only be properly addressed by detailed longitudinal studies in which an attempt is made to collect more comprehensive vocabulary records for individual children.