Individual Differences In Language Development Research Articles

Early, typical, and late talkers: an exploratory study on predictors of language development in the first two years of life.

The consensus in scientific literature is that each child undergoes a unique linguistic development path, albeit with shared developmental stages. Some children excel or lag behind their peers in language skills. Consequently, a key challenge in language acquisition research is pinpointing factors influencing individual differences in language development. We observed children longitudinally from 3 to 24 months of life to explore early predictors of vocabulary size. Based on the productive vocabulary size of children at 24 months, 30 children met our sample selection criteria: 10 late talkers and 10 early talkers, and we compared them with 10 typical talkers. We evaluated interactive behaviors at 3, 6, 9 and 12 months, considering vocal production, gaze at mother's face, and gestural production during mother-child interactions, and we considered mothers' report of children's actions and gestures and receptive-vocabulary size at 15 and 18 months. Results indicated early precursors of language outcome at 24 months identifiable as early as 3 months in vocal productions, 6 months for gaze at mother's face and 12 months for gestural productions. Our research highlights both theoretical and practical implications. Theoretically, identifying the early indicators of belonging to the group of late or early talkers underscores the significant role of this developmental period for future studies. On a practical note, our findings emphasize the crucial need for early investigations to identify predictors of vocabulary development before the typical age at which lexical delay is identified.

Introducing the Intra-Individual Variability Hypothesis in Explaining Individual Differences in Language Development.

Response times (RTs) are commonly used in studying language acquisition. However, previous research utilizing RT in the context of language has largely overlooked the intra-individual variability (IIV) of RTs, which could hold significant information about the processes underlying language acquisition. We explored the association between language abilities and RT variability in visuomotor tasks using two data sets from previously published studies. The participants were 7- to 10-year-old children (n = 77). Our results suggest that increased variability in RTs is associated with weaker language abilities. Specifically, this within-participant variability in visuomotor RTs, especially the proportion of unusually slow responses, predicted language abilities better than mean RTs, a factor often linked to language skills in past research. Based on our findings, we introduce the IIV hypothesis in explaining individual differences in language development. According to our hypothesis, inconsistency in the timing of cognitive processes, reflected by increased IIV in RTs, degrades learning different aspects of language, and results in individual differences in language abilities. Future studies should further examine the relationship between IIV and language abilities, and test the extent to which the possible relationship is causal.

Early developmental trajectories of expressive vocabulary and gesture production in a longitudinal cohort of Italian infants at high-risk for Autism Spectrum Disorder.

Delays in language are a hallmark feature of Autism Spectrum Disorder (ASD). However, little is known about the predictive role of language developmental trajectories on ASD. The present study aimed at identifying early different language developmental profiles of infants at high familial risk for ASD (HR-ASD) and testing their predictive role on ASD symptoms at 2 years. The role of gestures on socio-communicative skills has also been explored. Trajectories of expressive vocabulary were investigated in 137 HR-ASD infants at 12, 18, and, 24 months of age. Parents were requested to complete the Italian version of the MacArthur-Bates Communicative Development Inventory and ASD symptoms were measured by ADOS-2. Latent class growth analysis defined four trajectories: above average language development group (above-average LD, 18.2%), normal language development group (NLD, 38.7%), late-onset language development group (late-onset LD, 11.7%), and a group of children with stable language delay (SLD, 31.4%). Results showed that the SLD group obtained higher communicative difficulties and restricted/repetitive behavior compared to the other groups. Examining early increase of produced gestures in the different language classes, we found fewer produced gestures between 12 and 18 months in the SLD group compared to the late-onset LD group. The results identified clusters of HR infants who follow similar estimated trajectories based on individual differences in language development. These patterns of early language acquisition, together with produced gestures, may be predictive of later ASD symptoms and useful for planning prompt intervention. LAY SUMMARY: Language/gesture deficits are hallmark features of Autism Spectrum Disorder (ASD), but the predictive role of communicative trajectories on ASD remains unclear. In a longitudinal Italian sample of infants at high familial risk for ASD (HR-ASD), we tested if language trajectories and their link with gestures can predict ASD symptoms. We found four trajectories and HR infants with a stable language delay (SLD) trajectory showed more ASD symptoms later on. SLD infants produced fewer gestures compared to late-onset language development group that show more typical communicative skills.

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Procedural and declarative memory brain systems in developmental language disorder (DLD)

The aim of the current study was to examine microstructural differences in white matter relevant to procedural and declarative memory between adolescents/young adults with and without Developmental Language Disorder (DLD) using diffusion tensor imaging (DTI). The findings showed atypical age-related changes in white matter structures in the corticostriatal system, in the corticocerebellar system, and in the medial temporal region in individuals with DLD. Results highlight the importance of considering the age factor in research on DLD. Future studies are needed to examine the developmental relationship between long-term memory and individual differences in language development and learning.

Probing the Internal Validity of the LLAMA Language Aptitude Tests

AbstractOver the past decade, the LLAMA language aptitude test battery has come to play an increasingly important role as an instrument in research on individual differences in language development. However, a potentially serious problem that has been pointed out by several scholars is that the LLAMA has not yet been carefully validated. We addressed this issue by examining the internal validity of this test battery. We collected LLAMA data from 350 participants and assessed these data using classical item analysis, Rasch analysis, and principal component analysis within a framework of best practices in educational and psychological test validation. The results show that only one out of the four subtests (LLAMA B) produced scores that fit a latent trait model with sufficient accuracy. This suggests that researchers using the LLAMA battery must treat their results with appropriate carefulness and also that there is potential for refining the LLAMA further.

Language development and intelligence in midlife.

Individual differences in early language skills have been found to be associated with other cognitive outcomes in childhood and adolescence. However, research is limited on whether these associations persist into adulthood. In this study, we examined potential associations of the timing of early language milestones with cognitive ability in a prospective cohort study of 938 singletons from the Copenhagen Perinatal Cohort (CPC), who participated in a 50-year follow-up examination in 2009-2011. Later attainment of a number of milestones was associated with lower midlife IQ with the strongest associations found for 'Naming objects/animals in pictures', 'Forming a sentence', and 'Sharing experiences'. Milestones related to language explained 6.7% of the variance in midlife IQ, while milestones related to social interaction explained 3.1%. Thestudy provides evidence that individual differences in language development during the first years of life are associated with intelligence in midlife. Statement of contribution What is already known on this subject? Differences in early language skills are associated with other cognitive skills in childhood and adolescence. No study has examined this association from childhood through midlife in a large community-based sample. What does this study add? Early language development is associated with intelligence in midlife. A total of 6.7% of the variance in midlife IQ is explained by milestones related to language. Adjustment for potentially confounding factors did not change the associations.

Common Genetic Variants in FOXP2 Are Not Associated with Individual Differences in Language Development.

Much of our current knowledge regarding the association of FOXP2 with speech and language development comes from singleton and small family studies where a small number of rare variants have been identified. However, neither genome-wide nor gene-specific studies have provided evidence that common polymorphisms in the gene contribute to individual differences in language development in the general population. One explanation for this inconsistency is that previous studies have been limited to relatively small samples of individuals with low language abilities, using low density gene coverage. The current study examined the association between common variants in FOXP2 and a quantitative measure of language ability in a population-based cohort of European decent (n = 812). No significant associations were found for a panel of 13 SNPs that covered the coding region of FOXP2 and extended into the promoter region. Power analyses indicated we should have been able to detect a QTL variance of 0.02 for an associated allele with MAF of 0.2 or greater with 80% power. This suggests that, if a common variant associated with language ability in this gene does exist, it is likely of small effect. Our findings lead us to conclude that while genetic variants in FOXP2 may be significant for rare forms of language impairment, they do not contribute appreciably to individual variation in the normal range as found in the general population.

A genome-wide sib-pair scan for quantitative language traits reveals linkage to chromosomes 10 and 13.

Although there is considerable evidence that individual differences in language development are highly heritable, there have been few genome-wide scans to locate genes associated with the trait. Previous analyses of language impairment have yielded replicable evidence for linkage to regions on chromosomes 16q, 19q, 13q (within lab) and at 13q (between labs). Here we report the first linkage study to screen the continuum of language ability, from normal to disordered, as found in the general population. 383 children from 147 sib-ships (214 sib-pairs) were genotyped on the Illumina(®) Linkage IVb Marker Panel using three composite language-related phenotypes and a measure of phonological memory (PM). Two regions (10q23.33; 13q33.3) yielded genome-wide significant peaks for linkage with PM. A peak suggestive of linkage was also found at 17q12 for the overall language composite. This study presents two novel genetic loci for the study of language development and disorders, but fails to replicate findings by previous groups. Possible reasons for this are discussed.

Children with specific language impairment and their contribution to the study of language development.

Children with specific language impairment (SLI) are distinguishable from typically developing children primarily in the pace and course of their language development. For this reason, they are appropriate candidates for inclusion in any theory of language acquisition. In this paper, the areas of overlap between children with SLI and those developing in typical fashion are discussed, along with how the joint study of these two populations can enhance our understanding of the language development process. In particular, evidence from children with SLI can provide important information concerning the role of language typology in language development, the optimal ages for acquiring particular linguistic details, the robustness of the bilingual advantage for children, the role of input in children's acquisition of grammatical details, the unintended influence of processing demands during language assessment, the contributions of treatment designs to the study of typically developing children, and the study of individual differences in language development.

Cognitive and Neural Mechanisms Underlying Socioeconomic Gradients in Language Development: New Answers to Old Questions

AbstractAlthough researchers have studied disparities in early language development related to socioeconomic status (SES), it is unclear how early and through which mechanisms these differences emerge. As income inequality continues to widen across the world, it is crucial to examine the child‐level mechanisms that mediate the effects of SES on individual differences in language development. A deeper understanding of the nature of the differences will allow development of more effective intervention techniques. In this article, we discuss work on child‐level cognitive and neural mechanisms underlying the relation between SES and early language development. We discuss possible factors behind individual differences in child‐level mechanisms and cascading effects of these differences. We conclude with recommendations for research.

Childhood Verbal Development and Drinking Behaviors from Adolescence to Young Adulthood: A Discordant Twin-Pair Analysis

Studies suggest that better cognitive and verbal abilities in childhood predict earlier experimentation with alcohol and higher levels of drinking in adolescence, whereas poorer ability is related to a higher likelihood of remaining abstinent. Whether individual differences in language development in childhood predict differences in adolescent drinking behaviors has not been studied. To address that question, we compared co-twins from twin pairs discordant for their childhood language development and studied associations of parental reports of within-pair differences in age at speaking words, age at learning to read, and expressive language skills during school age with self-reported within-pair differences in drinking, intoxication, and alcohol-related problems across adolescence and young adulthood. Data from 2 longitudinal population-based samples of twin families were used, with verbal developmental differences in childhood reported by the parents when the twins were 12 and 16years of age, respectively. Conditional logistic regression analyses and within-pair correlation analyses suggested positive associations between verbal development and drinking behaviors in both data sets. In analyses adjusted for birth order and birth weight, the co-twin reported to be verbally more advanced in childhood tended to report more frequent drinking and intoxication in adolescence in both samples. Better verbal development also was associated with the likelihood of having friends who drink in adolescence. These findings suggest that, adjusting for familial and other factors shared by co-twins, better verbal development in childhood predicts more frequent drinking and intoxication in adolescence and young adulthood, possibly due, in part, to peer associations.

Abnormal subcortical components of the corticostriatal system in young adults with DLI: A combined structural MRI and DTI study

Developmental Language Impairment (DLI) is a neurodevelopmental disorder affecting 12% to 14% of the school-age children in the United States. While substantial studies have shown a wide range of linguistic and non-linguistic difficulty in individuals with DLI, very little is known about the neuroanatomical mechanisms underlying this disorder. In the current study, we examined the subcortical components of the corticostriatal system in young adults with DLI, including the caudate nucleus, the putamen, the nucleus accumbens, the globus pallidus, and the thalamus. Additionally, the four cerebral lobes and the hippocampus were also comprised for an exploratory analysis. We used conventional magnetic resonance imaging (MRI) to measure regional brain volumes, as well as diffusion tensor imaging (DTI) to assess water diffusion anisotropy as quantified by fractional anisotropy (FA). Two groups of participants, one with DLI (n=12) and the other without (n=12), were recruited from a prior behavioral study, and all were matched on age, gender, and handedness. Volumetric analyses revealed region-specific abnormalities in individuals with DLI, showing pathological enlargement bilaterally in the putamen and the nucleus accumbens, and unilaterally in the right globus pallidus after the intracranial volumes were controlled. Regarding the DTI findings, the DLI group showed decreased FA values in the globus pallidus and the thalamus but these significant differences disappeared after controlling for the whole-brain FA value, indicating that microstructural abnormality is diffuse and affects other regions of the brain. Taken together, these results suggest region-specific corticostriatal abnormalities in DLI at the macrostructural level, but corticostriatal abnormalities at the microstructural level may be a part of a diffuse pattern of brain development. Future work is suggested to investigate the relationship between corticostriatal connectivity and individual differences in language development.

Developmental trends in auditory processing can provide early predictions of language acquisition in young infants

Auditory processing capabilities at the subcortical level have been hypothesized to impact an individual's development of both language and reading abilities. The present study examined whether auditory processing capabilities relate to language development in healthy 9-month-old infants. Participants were 71 infants (31 boys and 40 girls) with both Auditory Brainstem Response (ABR) and language assessments. At 6 weeks and/or 9 months of age, the infants underwent ABR testing using both a standard hearing screening protocol with 30 dB clicks and a second protocol using click pairs separated by 8, 16, and 64-ms intervals presented at 80 dB. We evaluated the effects of interval duration on ABR latency and amplitude elicited by the second click. At 9 months, language development was assessed via parent report on the Chinese Communicative Development Inventory - Putonghua version (CCDI-P). Wave V latency z-scores of the 64-ms condition at 6 weeks showed strong direct relationships with Wave V latency in the same condition at 9 months. More importantly, shorter Wave V latencies at 9 months showed strong relationships with the CCDI-P composite consisting of phrases understood, gestures, and words produced. Likewise, infants who had greater decreases in Wave V latencies from 6 weeks to 9 months had higher CCDI-P composite scores. Females had higher language development scores and shorter Wave V latencies at both ages than males. Interestingly, when the ABR Wave V latencies at both ages were taken into account, the direct effects of gender on language disappeared. In conclusion, these results support the importance of low-level auditory processing capabilities for early language acquisition in a population of typically developing young infants. Moreover, the auditory brainstem response in this paradigm shows promise as an electrophysiological marker to predict individual differences in language development in young children.

Temperamental profiles and language development: A replication and an extension

Individual differences in child temperament are associated with individual differences in language development. The present study examined the relationship between temperament and language ability in 109 twenty-four- to 30-month-old children. Parents and day-care teachers completed two questionnaires: the Primo Vocabolario del Bambino ( Caselli & Casadio, 1995) and the Questionari Italiani del Temperamento ( Axia, 2002). Researchers administered the First Language Test ( Axia, 1993) to assess productive and receptive language in each child. Replicating previous research ( Usai, Garello, & Viterbori, 2009), day-care teachers identified three temperamental profiles: most of the children fit into the first profile, typical of the Italian population; another profile was made up of easily distractible and not very persistent children, with a poor capacity to modulate motor activity; and the third profile of children were inhibited in new situations. A relationship was found between temperament assessed by day-care teachers and different levels of linguistic competence. In particular, the groups of “inattentive” and “inhibited” children showed poorer lexical and morphological abilities and a more immature vocabulary, characterised by the presence of more primitive components of the lexical repertory compared to the group of “typical” children. Unlike the results from day-care teachers, temperament questionnaires completed by parents revealed a 4-cluster-solution. Also, for parents, the “typical” profile is characterised by the largest vocabulary (productive and receptive) and the most mature semantic production.

C082 Effects of early cochlea implantation on reading

Individual differences in child temperament are associated with individual differences in language development. The present study examined the relationship between temperament and language ability in 109 twenty-four- to 30-month-old children. Parents and day-care teachers completed two questionnaires: the Primo Vocabolario del Bambino (Caselli & Casadio, 1995) and the Questionari Italiani del Temperamento (Axia, 2002). Researchers administered the First Language Test (Axia, 1993) to assess productive and receptive language in each child.Replicating previous research (Usai, Garello, & Viterbori, 2009), day-care teachers identified three temperamental profiles: most of the children fit into the first profile, typical of the Italian population; another profile was made up of easily distractible and not very persistent children, with a poor capacity to modulate motor activity; and the third profile of children were inhibited in new situations. A relationship was found between temperament assessed by day-care teachers and different levels of linguistic competence. In particular, the groups of “inattentive” and “inhibited” children showed poorer lexical and morphological abilities and a more immature vocabulary, characterised by the presence of more primitive components of the lexical repertory compared to the group of “typical” children. Unlike the results from day-care teachers, temperament questionnaires completed by parents revealed a 4-cluster-solution. Also, for parents, the “typical” profile is characterised by the largest vocabulary (productive and receptive) and the most mature semantic production.

Individual differences in language development: relationship with motor skill at 21 months

Language development has long been associated with motor development, particularly manual gesture. We examined a variety of motor abilities - manual gesture including symbolic, meaningless and sequential memory, oral motor control, gross and fine motor control - in 129 children aged 21 months. Language abilities were assessed and cognitive and socio-economic measures controlled for. Oral motor control was strongly associated with language production (vocabulary and sentence complexity), with some contribution from symbolic abilities. Language comprehension, however, was associated with cognitive and socio-economic measures. We conclude that symbolic, working memory, and mirror neuron accounts of language-motor control links are limited, but that a common neural and motor substrate for nonverbal and verbal oral movements may drive the motor-language association.

Gaze behavior and affect at 6 months: predicting clinical outcomes and language development in typically developing infants and infants at risk for autism

This paper presents follow-up longitudinal data to research that previously suggested the possibility of abnormal gaze behavior marked by decreased eye contact in a subgroup of 6-month-old infants at risk for autism (Merin, Young, Ozonoff & Rogers, 2007). Using eye-tracking data and behavioral data recorded during a live mother-infant interaction involving the still-face procedure, the predictive utility of gaze behavior and affective behaviors at 6 months was examined using diagnostic outcome data obtained longitudinally over the following 18 months. Results revealed that none of the infants previously identified as showing lower rates of eye contact had any signs of autism at outcome. In contrast, three infants who were diagnosed with autism demonstrated consistent gaze to the eye region and typical affective responses at 6 months. Individual differences in face scanning and affective responsivity during the live interaction were not related to any continuous measures of symptom frequency or symptom severity. In contrast, results of growth curve models for language development revealed significant relationships between face scanning and expressive language. Greater amounts of fixation to the mother's mouth during live interaction predicted higher levels of expressive language at outcome and greater rates of growth. These findings suggest that although gaze behavior at 6 months may not provide early markers for autism as initially conceived, gaze to the mouth in particular may be useful in predicting individual differences in language development.

Temperamental and Joint Attentional Predictors of Language Development.

Individual differences in child temperament have been associated with individual differences in language development. Similarly, relationships have been reported between early nonverbal social communication (joint attention) and both temperament and language. The present study examined whether individual differences in joint attention might mediate temperament-language relationships. Temperament, language, and joint attention were assessed in 51 21-month-olds. Results indicated an inverse relationship between aspects of temperamental difficulty, including low executive control and high negative affect, and language development. Temperamental aspects of negative affect were also inversely predictive of joint attention. However, the utility of a model in which joint attention mediates the relationship between temperament and language during the second year was not supported.

EEG coherence, joint attention and language development in the second year

AbstractRecent research has raised the hypothesis that brain maturation processes may play an important role in the linkage between infant joint attention and language development. This hypothesis was examined using EEG, joint attention and parent report language measures in a longitudinal study of 29 infants assessed at 14, 18 and 24 months of age. The results indicated that both measures of joint attention and EEG coherence at 14 months were related to language development at 24 months. Furthermore, both EEG coherence measures and joint attention measures made contributions to multiple regression equations predicting individual differences in language development. Finally, coherence data from this study were consistent withThatcher's (1994) theory of different patterns of neural integration and differentiation in the early maturation of the left and right hemispheres. The implications of these results for understanding the nature of the relations between joint attention and language development, as well as the utility of EEG coherence measures in developmental neuroscience are discussed.