Disentangling the effects of cognitive development and linguistic expertise: A longitudinal study of the acquisition of English in internationally-adopted children

Disentangling the roles of age and knowledge in early language acquisition: A fine-grained analysis of the vocabularies of infant and child language learners

The words that children learn change over time in predictable ways. The first words that infants acquire are generally ones that are both frequent and highly imageable. Older infants also learn words that are more abstract and some that are less common. It is unclear whether this pattern is attributable to maturational factors (i.e., younger children lack sufficiently developed cognitive faculties needed to learn abstract words) or linguistic factors (i.e., younger children lack sufficient knowledge of their language to use grammatical or contextual cues needed to figure out the meaning of more abstract words). The present study explores this question by comparing vocabulary acquisition in 53 preschool-aged children (M = 51 months, range = 30-76 months) who were adopted from China and Eastern Europe after two and half years of age and 53 vocabulary-matched infant controls born and raised in English speaking families in North America (M = 24 months, range = 16-33 months). Vocabulary was assessed using the MB-CDI Words and Sentences form, word frequency was estimated from the CHILDES database, and imageability was measured using adult ratings of how easily words could be pictured mentally. Both groups were more likely to know words that were both highly frequent and imageable (resulting in an over-additive interaction). Knowledge of a word was also independently affected by the syntactic category that it belongs to. Adopted preschoolers' vocabulary was slightly less affected by imageability. These findings were replicated in a comparison with a larger sample of vocabulary-matched controls drawn from the MB-CDI norming study (M = 22 months, range = 16-30 months; 33 girls). These results suggest that the patterns of acquisition in children's early vocabulary are primarily driven by the accrual of linguistic knowledge, but that vocabulary may also be affected by differences in early life experiences or conceptual knowledge.

It's All in the Interaction: Early Acquired Words Are Both Frequent and Highly Imageable

Prior studies have found that children are more likely to learn words that are frequent in the input and highly imageable. Many theories of word learning, however, predict that these variables should interact, particularly early in development: frequency of a form is of little use if you cannot infer its meaning, and a concrete word cannot be acquired if you never hear it. The present study explores this interaction, how it changes over time and its relationship to syntactic category effects in children acquiring American English. We analyzed 1461 monolingual English-speaking children aged 1;4-2;6 from the MB-CDI norming study (Fenson et al., 1994). Word frequency was estimated from the CHILDES database, and imageability was measured using adult ratings. There was a strong over-additive interaction between frequency and imageability, such that children were more likely to learn a word if it was both highly imageable and very frequent. This interaction was larger in younger children than in older children. There were reliable differences between syntactic categories independent of frequency and imageability, which did not interact with age. These findings are consistent with theories in which children's early words are acquired by mapping frequent word forms onto concrete, perceptually available referents, such that highly frequent items are only acquired if they are also imageable, and vice versa.

The more they hear the more they learn? Using data from bilinguals to test models of early lexical development

Children have an early ability to learn and comprehend words, a skill that develops as they age. A critical question remains regarding what drives this development. Maturation-based theories emphasise cognitive maturity as a driver of comprehension, while accumulator theories emphasise children's accumulation of language experience over time. In this study we used archival looking-while-listening data from 155 children aged 14-48 months with a range of exposure to the target languages (from 10% to 100%) to evaluate the relative contributions of maturation and experience. We compared four statistical models of noun learning: maturation-only, experience-only, additive (maturation plus experience), and accumulator (maturation times experience). The best-fitting model was the additive model in which both maturation (age) and experience were independent contributors to noun comprehension: older children as well as children who had more experience with the target language were more accurate and looked faster to the target in the looking-while-listening task. A 25% change in relative language exposure was equivalent to a 4 month change in age, and age effects were stronger at younger than at older ages. Whereas accumulator models predict that the lexical development of children with less exposure to a language (as is typical in bilinguals) should fall further and further behind children with more exposure to a language (such as monolinguals), our results indicate that bilinguals are buffered against effects of reduced exposure in each language. This study shows that continuous-level measures from individual children's looking-while-listening data, gathered from children with a range of language experience, provide a powerful window into lexical development.

Children’s syntax is supported by the maturation of BA44 at 4 years, but of the posterior STS at 3 years of age

Within the first years of life, children learn major aspects of their native language. However, the ability to process complex sentence structures, a core faculty in human language called syntax, emerges only slowly. A milestone in syntax acquisition is reached around the age of 4 years, when children learn a variety of syntactic concepts. Here, we ask which maturational changes in the child’s brain underlie the emergence of syntactically complex sentence processing around this critical age. We relate markers of cortical brain maturation to 3- and 4-year-olds’ sentence processing in contrast to other language abilities. Our results show that distinct cortical brain areas support sentence processing in the two age groups. Sentence production abilities at 3 years were associated with increased surface area in the most posterior part of the left superior temporal sulcus, whereas 4-year-olds showed an association with cortical thickness in the left posterior part of Broca’s area, i.e. BA44. The present findings suggest that sentence processing abilities rely on the maturation of distinct cortical regions in 3- compared to 4-year-olds. The observed shift to more mature regions involved in processing syntactically complex sentences may underlie behavioral milestones in syntax acquisition at around 4 years.

Characteristics of Early Expressive Vocabulary in Mandarin-Speaking Children With Cochlear Implants

PURPOSE

The aim of this study is to evaluate whether Mandarin-speaking children with cochlear implants (CIs) demonstrated early lexical composition similar to their hearing peers who were at the same vocabulary level and the extent to which children with CIs were sensitive to linguistic and conceptual properties when developing early lexicon.

METHOD

Participants were 77 Mandarin-speaking children with CIs who received CIs before 30 months of age. Their expressive vocabulary was documented using the Infant Checklist of the Early Vocabulary Inventory for Mandarin Chinese 9 or 12 months after CI activation. Percent social words, common nouns, predicates (verbs, adjectives), and closed-class words in total vocabulary were computed for children at different vocabulary levels. Common nouns and verbs were further coded for their word class (noun, verb), word frequency, word length, and imageability to predict how likely a given noun or verb would be produced by children with CIs.

RESULTS

Like children with typical hearing, social words were the most dominant category when vocabulary size in children with CIs was smaller than 20 words; common nouns became the most dominant category when the vocabulary size reached 21 words. The difference in percent common nouns and percent predicates (i.e., noun bias) was similar in children with CIs and their hearing peers. In addition, verbs, common words, monosyllabic words, and more imageable words were more likely to be produced by children with CIs than their counterparts.

CONCLUSIONS

Mandarin children with CIs showed language-specific patterns in early lexical composition like their hearing peers. They were able to use multiple linguistic and conceptual cues when approaching early expressive vocabulary despite perceptual and processing constraints.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.21357723.

The development of early numeracy in deaf and hard of hearing children acquiring spoken language

Most deaf and hard-of-hearing (DHH) children are born to hearing parents and steered toward spoken rather than signed language, introducing a delay in language access. This study investigated the effects of this delay on number acquisition. DHH children (N = 44, mean_age  = 58 months, 21F, >50% White) and typically-hearing (TH) children (N = 79, mean_age  = 49 months, 51F, >50% White) were assessed on number and language in 2011-13. DHH children showed similar trajectories to TH children but delayed timing; a binary logistic regression showed that the odds of being a cardinal-principle (CP) knower were 17 times higher for TH children than DHH children, controlling for age (d = .69). Language fully mediated the association between deaf/hearing group and number knowledge, suggesting that language access sets the pace for number acquisition.

The effects of maternal input on language in the absence of genetic confounds: Vocabulary development in internationally adopted children

Previous studies have found correlations between parent input and child language outcomes, providing prima facie evidence for a causal relation. However, this could also reflect the effects of shared genes. The present study removed this genetic confound by measuring English vocabulary growth in 29 preschool-aged children (21 girls) aged 31-73 months and 17 infants (all girls) aged 15-32 months adopted from China and Eastern Europe and comparing it to speech produced by their adoptive mothers. Vocabulary growth in both groups was correlated with maternal input features; in infants with mean-length of maternal utterance, and in preschoolers with both mean-length of utterance and lexical diversity. Thus, input effects on language outcomes persist even in the absence of genetic confounds.

Lack of selectivity for syntax relative to word meanings throughout the language network

To understand what you are reading now, your mind retrieves the meanings of words and constructions from a linguistic knowledge store (lexico-semantic processing) and identifies the relationships among them to construct a complex meaning (syntactic or combinatorial processing). Do these two sets of processes rely on distinct, specialized mechanisms or, rather, share a common pool of resources? Linguistic theorizing, empirical evidence from language acquisition and processing, and computational modeling have jointly painted a picture whereby lexico-semantic and syntactic processing are deeply inter-connected and perhaps not separable. In contrast, many current proposals of the neural architecture of language continue to endorse a view whereby certain brain regions selectively support syntactic/combinatorial processing, although the locus of such "syntactic hub", and its nature, vary across proposals. Here, we searched for selectivity for syntactic over lexico-semantic processing using a powerful individual-subjects fMRI approach across three sentence comprehension paradigms that have been used in prior work to argue for such selectivity: responses to lexico-semantic vs. morpho-syntactic violations (Experiment 1); recovery from neural suppression across pairs of sentences differing in only lexical items vs. only syntactic structure (Experiment 2); and same/different meaning judgments on such sentence pairs (Experiment 3). Across experiments, both lexico-semantic and syntactic conditions elicited robust responses throughout the left fronto-temporal language network. Critically, however, no regions were more strongly engaged by syntactic than lexico-semantic processing, although some regions showed the opposite pattern. Thus, contra many current proposals of the neural architecture of language, syntactic/combinatorial processing is not separable from lexico-semantic processing at the level of brain regions-or even voxel subsets-within the language network, in line with strong integration between these two processes that has been consistently observed in behavioral and computational language research. The results further suggest that the language network may be generally more strongly concerned with meaning than syntactic form, in line with the primary function of language-to share meanings across minds.

Lack of selectivity for syntax relative to word meanings throughout the language network

To understand what you are reading now, your mind retrieves the meanings of words and constructions from a linguistic knowledge store (lexico-semantic processing) and identifies the relationships among them to construct a complex meaning (syntactic or combinatorial processing). Do these two sets of processes rely on distinct, specialized mechanisms or, rather, share a common pool of resources? Linguistic theorizing, empirical evidence from language acquisition and processing, and computational modeling have jointly painted a picture whereby lexico-semantic and syntactic processing are deeply inter-connected and perhaps not separable. In contrast, many current proposals of the neural architecture of language continue to endorse a view whereby certain brain regions selectively support syntactic/combinatorial processing, although the locus of such "syntactic hub", and its nature, vary across proposals. Here, we searched for selectivity for syntactic over lexico-semantic processing using a powerful individual-subjects fMRI approach across three sentence comprehension paradigms that have been used in prior work to argue for such selectivity: responses to lexico-semantic vs. morpho-syntactic violations (Experiment 1); recovery from neural suppression across pairs of sentences differing in only lexical items vs. only syntactic structure (Experiment 2); and same/different meaning judgments on such sentence pairs (Experiment 3). Across experiments, both lexico-semantic and syntactic conditions elicited robust responses throughout the left fronto-temporal language network. Critically, however, no regions were more strongly engaged by syntactic than lexico-semantic processing, although some regions showed the opposite pattern. Thus, contra many current proposals of the neural architecture of language, syntactic/combinatorial processing is not separable from lexico-semantic processing at the level of brain regions-or even voxel subsets-within the language network, in line with strong integration between these two processes that has been consistently observed in behavioral and computational language research. The results further suggest that the language network may be generally more strongly concerned with meaning than syntactic form, in line with the primary function of language-to share meanings across minds.

Early Vocabulary Profiles of Young Deaf Children Who Use Cochlear Implants

Purpose This study examined vocabulary profiles in young cochlear implant (CI) recipients and in children with normal hearing (NH) matched on receptive vocabulary size to improve our understanding of young CI recipients' acquisition of word categories (e.g., common nouns or closed-class words). Method We compared receptive and expressive vocabulary profiles between young CI recipients (n = 48; mean age at activation = 15.61 months, SD = 4.20) and children with NH (n = 48). The two groups were matched on receptive vocabulary size as measured by the MacArthur-Bates Communicative Development Inventories (Fenson et al., 2006): Words and Gestures form. The CI group had, on average, 8.98 months of hearing experience. The mean chronological age at completing the MacArthur-Bates Communicative Development Inventories was 23.99 months (SD = 5.14) for the CI group and 13.72 months (SD = 1.50) for the NH group. Results The CI group had a larger expressive vocabulary size than the receptive vocabulary size-matched NH group. The larger expressive vocabulary size was associated with the group difference in social words but not with common nouns. The analyses for predicate words and closed-class words included only children who produced the target categories. The CI group had a larger proportion of predicate words than the NH group, but no difference was found in closed-class words in expressive vocabulary. Conclusions Differences found in expressive vocabulary profiles may be affected by spoken vocabulary size and their age. A further examination is warranted using language samples to understand the effect of language input on children's vocabulary profiles.

I’m Doing Better on My Own: Social Inhibition in Vocabulary Learning in Adults

Vocabulary learning is better achieved by children facing a teacher than when presented to the same teacher through video (so-called “video deficit” effect), which has significant implications for toddlers’ education. Since millions of adults also learn new vocabulary when acquiring a second language (L2), it is important to explore whether adults suffer from “video deficit” effects, as children do. In the present study, we report two experiments in which Spanish native late learners of English were involved in a vocabulary learning task. In Experiment 1, participants had to learn English (L2) labels associated to real objects. In Experiment 2, participants had to learn English (L2) and Spanish (L1) labels associated to novel objects. In both experiments, vocabulary learning was divided into three conditions: In the NoFace condition, participants were presented with the objects and their auditory labels, through video. In the Video condition, a teacher was showing the objects and uttering their names, through video. The Live condition was equivalent, except that the teacher was facing the participants in the room. Each condition was followed by a recall test. Better learning in Video compared to NoFace condition revealed that adults benefit from the teacher’s display with direct gaze, confirming the fundamental role of face display with direct gaze in social communication in adults. Interestingly, adults learned better through Video than in the Live condition. Those results were obtained in L2 vocabulary learning in both Experiments 1 and 2, and also generalized to native language in Experiment 2. We argue that adults suffer from social inhibition, meaning that they perform worse when in the presence of another person during task performance. In sum, we show that video-mediated teaching might not be detrimental for adults learning new vocabulary lists, as it is the case for young children. These results might have important implications for pedagogical programs targeting adults’ second language vocabulary learning, since proper acquisition of vocabulary list can be achieved through video including a teacher’s display.

Narrative abilities of bilingual children with and without Developmental Language Disorder (SLI): Differentiation and the role of age and input factors

PURPOSE

The narrative abilities of bilinguals with TD and with DLD/SLI in their English L2 were examined in order to 1) identify the narrative components that differentiate these two groups and 2) determine the role of age and input factors in predicting L2 narrative abilities in each group.

METHOD

Participants were 24 English L2 children with DLD and 63 English L2 children with TD, matched on age (mean = 5; 8) and length of exposure to the L2 (mean = 24 months). Narrative samples were elicited using a story generation task and a parent questionnaire provided age and input variables.

RESULTS

Bilinguals with DLD had significantly lower scores for story grammar than their TD peers, but showed similar scores for narrative microstructure components. Length of L2 exposure in school and richness of the L2 environment predicted better narrative abilities for the group with TD but not with DLD. Older age predicted better narrative abilities for the group with DLD but not with TD. Quantity of L2 input/output at home did not predict story grammar or microstructure abilities in either group.

CONCLUSION

Story grammar might differentiate between children with TD and DLD better than microstructure among bilinguals with less exposure to the L2 and when a story generation task is used. Bilinguals with TD make more efficient use of L2 input than bilinguals with DLD.

What explains the correlation between growth in vocabulary and grammar? New evidence from latent change score analyses of simultaneous bilingual development

A close relationship between children's vocabulary size and the grammatical complexity of their speech is well attested but not well understood. The present study used latent change score modeling to examine the dynamic relationships between vocabulary and grammar growth within and across languages in longitudinal data from 90 simultaneous Spanish-English bilingual children who were assessed at 6-month intervals between 30 and 48 months. Slopes of vocabulary and grammar growth were strongly correlated within each language and showed moderate or nonsignificant relationships across languages. There was no evidence that vocabulary level predicted subsequent grammar growth or that the level of grammatical development predicted subsequent vocabulary growth. We propose that a common influence of properties of input on vocabulary and grammatical development is the source of their correlated but uncoupled growth. An unanticipated across-language finding was a negative relationship between level of English skill and subsequent Spanish growth. We propose that the cultural context of Spanish-English bilingualism in the US is the reason that strong English skills jeopardize Spanish language growth, while Spanish skills do not affect English growth. A video abstract of this article can be viewed at: https://youtu.be/qEHSQ0yRre0.

The emergence of temporal language in Nicaraguan Sign Language

Understanding what uniquely human properties account for the creation and transmission of language has been a central goal of cognitive science. Recently, the study of emerging sign languages, such as Nicaraguan Sign Language (NSL), has offered the opportunity to better understand how languages are created and the roles of the individual learner and the community of users. Here, we examined the emergence of two types of temporal language in NSL, comparing the linguistic devices for conveying temporal information among three sequential age cohorts of signers. Experiment 1 showed that while all three cohorts of signers could communicate about linearly ordered discrete events, only the second and third generations of signers successfully communicated information about events with more complex temporal structure. Experiment 2 showed that signers could discriminate between the types of temporal events in a nonverbal task. Finally, Experiment 3 investigated the ordinal use of numbers (e.g., first, second) in NSL signers, indicating that one strategy younger signers might have for accurately describing events in time might be to use ordinal numbers to mark each event. While the capacity for representing temporal concepts appears to be present in the human mind from the onset of language creation, the linguistic devices to convey temporality do not appear immediately. Evidently, temporal language emerges over generations of language transmission, as a product of individual minds interacting within a community of users.

The sooner the better? An investigation into the role of age of onset and its relation with transfer and exposure in bilingual Frisian-Dutch children

In this study, age of onset (AoO) was investigated in five- and six-year-old bilingual Frisian-Dutch children. AoO to Dutch ranged between zero and four and had a positive effect on Dutch receptive vocabulary size, but hardly influenced the children's accurate use of Dutch inflection. The influence of AoO on vocabulary was more prominent than the influence of exposure. Regarding inflection, the reverse was found. Accuracy at using Frisian inflection emerged as a significant predictor; this transfer effect was modulated by lexical overlap between the two languages. This study shows that 'the sooner the better' does not necessarily hold for language development. In fact, for the correct use of inflection, it does not matter whether children start at age zero or four. For rapidly learning words in a new language it may be helpful to first build a substantial vocabulary in the first language before learning a new language.

A Longitudinal Study of Language and Speech in Children Who Were Internationally Adopted at Different Ages

Purpose

The author followed 56 internationally adopted children during the first 3 years after adoption to determine how and when they reached age-expected language proficiency in Standard American English. The influence of age of adoption was measured, along with the relationship between early and later language and speech outcomes.

Method

Children adopted from Eastern Europe at ages 12 months to 4 years, 11 months, were assessed 5 times across 3 years. Norm-referenced measures of receptive and expressive language and articulation were compared over time. In addition, mean length of utterance (MLU) was measured.

Results

Across all children, receptive language reached age-expected levels more quickly than expressive language. Children adopted at ages 1 and 2 “caught up” more quickly than children adopted at ages 3 and 4. Three years after adoption, there was no difference in test scores across age of adoption groups, and the percentage of children with language or speech delays matched population estimates. MLU was within the average range 3 years after adoption but significantly lower than other language test scores.

Conclusions

Three years after adoption, age of adoption did not influence language or speech outcomes, and most children reached age-expected language levels. Expressive syntax as measured by MLU was an area of relative weakness.

Children's learning of number words in an indigenous farming-foraging group

We show that children in the Tsimane', a farming-foraging group in the Bolivian rain-forest, learn number words along a similar developmental trajectory to children from industrialized countries. Tsimane' children successively acquire the first three or four number words before fully learning how counting works. However, their learning is substantially delayed relative to children from the United States, Russia, and Japan. The presence of a similar developmental trajectory likely indicates that the incremental stages of numerical knowledge - but not their timing - reflect a fundamental property of number concept acquisition which is relatively independent of language, culture, age, and early education.

Word comprehension and production asymmetries in children and adults

Two studies investigated differences in the comprehension and production of words in 2-year-old children and adults. Study 1 compared children's speaking and understanding of the names of 12 novel objects presented over three weekly sessions. Study 2 tested adults' performance under similar training and testing conditions over two sessions. The findings indicated a comprehension advantage for both age groups. A fine-grained temporal analysis of individual words revealed that acquisition does not resemble a linear stage-wise progression from comprehension to production. Rather, dimensions of lexical knowledge develop at different rates, with words acquired, lost, and maintained over the course of learning. The findings support a dynamic and graded view of lexical processing and have implications for understanding what it means to know a word.