Attention to lexical stress and early vocabulary growth in 5-month-olds at risk for autism spectrum disorder

Predicting Social Competence in Autistic and Non-Autistic Children: Effects of Prosody and the Amount of Speech Input

PURPOSE

Autistic individuals often face challenges perceiving and expressing emotions, potentially stemming from differences in speech prosody. Here we explore how autism diagnoses between groups, and measures of social competence within groups may be related to, first, children's speech characteristics (both prosodic features and amount of spontaneous speech), and second, to these two factors in mothers' speech to their children.

METHODS

Autistic (n = 21) and non-autistic (n = 18) children, aged 7-12 years, participated in a Lego-building task with their mothers, while conversational speech was recorded. Mean F0, pitch range, pitch variability, and amount of spontaneous speech were calculated for each child and their mother.

RESULTS

The results indicated no differences in speech characteristics across autistic and non-autistic children, or across their mothers, suggesting that conversational context may have large effects on whether differences between autistic and non-autistic populations are found. However, variability in social competence within the group of non-autistic children (but not within autistic children) was predictive of children's mean F0, pitch range and pitch variability. The amount of spontaneous speech produced by mothers (but not their prosody) predicted their autistic children's social competence, which may suggest a heightened impact of scaffolding for mothers of autistic children.

CONCLUSION

Together, results suggest complex interactions between context, social competence, and adaptive parenting strategies in driving prosodic differences in children's speech.

Neural Tracking in Infancy Predicts Language Development in Children With and Without Family History of Autism

During speech processing, neural activity in non-autistic adults and infants tracks the speech envelope. Recent research in adults indicates that this neural tracking relates to linguistic knowledge and may be reduced in autism. Such reduced tracking, if present already in infancy, could impede language development. In the current study, we focused on children with a family history of autism, who often show a delay in first language acquisition. We investigated whether differences in tracking of sung nursery rhymes during infancy relate to language development and autism symptoms in childhood. We assessed speech-brain coherence at either 10 or 14 months of age in a total of 22 infants with high likelihood of autism due to family history and 19 infants without family history of autism. We analyzed the relationship between speech-brain coherence in these infants and their vocabulary at 24 months as well as autism symptoms at 36 months. Our results showed significant speech-brain coherence in the 10- and 14-month-old infants. We found no evidence for a relationship between speech-brain coherence and later autism symptoms. Importantly, speech-brain coherence in the stressed syllable rate (1-3 Hz) predicted later vocabulary. Follow-up analyses showed evidence for a relationship between tracking and vocabulary only in 10-month-olds but not in 14-month-olds and indicated possible differences between the likelihood groups. Thus, early tracking of sung nursery rhymes is related to language development in childhood.

The Vocabulary of Infants with an Elevated Likelihood and Diagnosis of Autism Spectrum Disorder: A Systematic Review and Meta-Analysis of Infant Language Studies Using the CDI and MSEL

Diagnoses of autism spectrum disorder (ASD) are typically accompanied by atypical language development, which can be noticeable even before diagnosis. The siblings of children diagnosed with ASD are at elevated likelihood for ASD diagnosis and have been shown to have higher prevalence rates than the general population. In this paper, we systematically reviewed studies looking at the vocabulary size and development of infants with autism. One inclusion criterion was that infants were grouped either pre-diagnostically as elevated or typical likelihood or post-diagnostically as ASD or without ASD. This review focused on studies that tested infants up to 24 months of age and that assessed vocabulary either via the parent-completed MacArthur–Bates Communicative Developmental Inventory (CDI) or the clinician-administered Mullen Scales of Early Learning (MSEL). Our systematic search yielded 76 studies. A meta-analysis was performed on these studies that compared the vocabulary scores of EL and TL infants pre-diagnostically and the scores of ASD and non-ASD infants post-diagnostically. Both pre- and post-diagnostically, it was found that the EL and ASD infants had smaller vocabularies than their TL and non-ASD peers, respectively. The effect sizes across studies were heterogenous, prompting additional moderator analyses of age and sub-group analyses of the language measure used (CDI or MSEL) as potential moderators of the effect size. Age was found to be a moderator both in the pre- and post-diagnostical groups, however, language measure was not a moderator in either diagnostic group. Interpretations and future research directions are discussed based on these findings.

Cross-linguistic contributions of acoustic cues and prosodic awareness to first and second language vocabulary knowledge

BACKGROUND

Several studies have revealed that prosody contributes to reading acquisition. However, the relation between awareness of prosodic patterns and different facets of language ability (e.g., vocabulary knowledge) in school-age children remains unclear. This study measured awareness of prosodic patterns using non-speech and speech stimuli.

METHODS

Hierarchical regression equations were computed to examine links among auditory cues (e.g., amplitude rise time, pitch contour and interval), language-specific prosodic awareness and children's vocabulary knowledge in Mandarin as a first language (L1) and English as a second language (L2) after controlling for age and nonverbal IQ.

RESULTS

Results revealed that (1) amplitude envelope rise time discrimination predicted Mandarin L1 and English L2 vocabulary knowledge, (2) Mandarin tone perception and rhyme awareness did not predict Mandarin L1 vocabulary and (3) English rhyme awareness better predicted English L2 vocabulary than did stress production.

CONCLUSION

Our findings suggest that (1) amplitude rise time, which signals syllable boundaries, is a cross-linguistic predictor of vocabulary knowledge and (2) the development of English L2 vocabulary may depend on phonological more than prosodic awareness.

Mandarin-speaking preschoolers' pitch discrimination, prosodic and phonological awareness, and their relation to receptive vocabulary and reading abilities

Cross-linguistic studies have reported that prosodic pattern awareness (e.g., lexical stress and lexical tone) is more important to reading acquisition than phonological awareness. However, few longitudinal studies have been conducted to explore the relations between these variables. This study examined preschoolers' pitch discrimination, prosodic and phonological awareness, and their connection to receptive vocabulary in preschool and reading abilities in first grade. Findings reveal (1) children improve their pitch discrimination and prosodic awareness from preschool to fourth grade; (2) pitch interval discrimination (frequency separation between tones) contributes to receptive vocabulary whereas pitch contour discrimination (patterns of rising and falling pitch) predicts word reading; (3) phonological awareness accounts for more variability in receptive vocabulary than prosodic awareness; whereas the reverse was found for word reading and reading comprehension. Together, prosody and its acoustic cue (i.e., pitch) play a vital role in learning to read Mandarin.

Lack of neural evidence for implicit language learning in 9-month-old infants at high risk for autism

Word segmentation is a fundamental aspect of language learning, since identification of word boundaries in continuous speech must occur before the acquisition of word meanings can take place. We previously used functional magnetic resonance imaging (fMRI) to show that youth with autism spectrum disorder (ASD) are less sensitive to statistical and speech cues that guide implicit word segmentation. However, little is known about the neural mechanisms underlying this process during infancy and how this may be associated with ASD risk. Here, we examined early neural signatures of language-related learning in 9-month-old infants at high (HR) and low familial risk (LR) for ASD. During natural sleep, infants underwent fMRI while passively listening to three speech streams containing strong statistical and prosodic cues, strong statistical cues only, or minimal statistical cues to word boundaries. Compared to HR infants, LR infants showed greater activity in the left amygdala for the speech stream containing statistical and prosodic cues. While listening to this same speech stream, LR infants also showed more learning-related signal increases in left temporal regions as well as increasing functional connectivity between bilateral primary auditory cortex and right anterior insula. Importantly, learning-related signal increases at 9 months positively correlated with expressive language outcome at 36 months in both groups. In the HR group, greater signal increases were additionally associated with less severe ASD symptomatology at 36 months. These findings suggest that early differences in the neural networks underlying language learning may predict subsequent language development and altered trajectories associated with ASD risk.

Infant speech perception and cognitive skills as predictors of later vocabulary

Research has identified bivariate correlations between speech perception and cognitive measures gathered during infancy as well as correlations between these individual measures and later language outcomes. However, these correlations have not all been explored together in prospective longitudinal studies. The goal of the current research was to compare how early speech perception and cognitive skills predict later language outcomes using a within-participant design. To achieve this goal, we tested 97 5- to 7-month-olds on two speech perception tasks (stress pattern preference, native vowel discrimination) and two cognitive tasks (visual recognition memory, A-not-B) and later assessed their vocabulary outcomes at 18 and 24 months. Frequentist statistical analyses showed that only native vowel discrimination significantly predicted vocabulary. However, Bayesian analyses suggested that evidence was ambiguous between null and alternative hypotheses for all infant predictors. These results highlight the importance of recognizing and addressing challenges related to infant data collection, interpretation, and replication in the developmental field, a roadblock in our route to understanding the contribution of domain-specific and domain-general skills for language acquisition. Future methodological development and research along similar lines is encouraged to assess individual differences in infant speech perception and cognitive skills and their predictability for language development.

Social endophenotypes in autism spectrum disorder: A scoping review

Endophenotypes are measurable markers of genetic vulnerability to current or future disorder. Autism spectrum disorder (ASD) is well-suited to be examined within an endophenotype framework given past and current emphases on the broader autism phenotype and early detection. We conducted a scoping review to identify potential socially-related endophenotypes of ASD. We focused on paradigms related to sociality (e.g., theory of mind (TOM), social attention), which comprise most of this literature. We integrated findings from traditional behavioral paradigms with brain-based measures (e.g., electroencephalography, functional magnetic resonance imaging). Broadly, infant research regarding social attention and responsivity (Research Domain Criteria (RDoC) domain of affiliation) and attention to faces and voices (social communication) finds consistent abnormality in vulnerable infant siblings. Several additional paradigms that have shown differences in vulnerable infants and young children include animacy perception tasks (perception and understanding of others), measures of recognition and response to familiar faces (attachment), and joint attention and false-belief tasks (understanding mental states). Research areas such as alexithymia (the perception and understanding of self), empathic responding, and vocal prosody may hold interest; however, challenges in measurement across populations and age ranges is a limiting factor. Future work should address sex differences and age dependencies, specificity to ASD, and heterogeneous genetic pathways to disorder within samples individuals with ASD and relatives.

Preference for speech in infancy differentially predicts language skills and autism-like behaviors

Early emerging biases for conspecific vocalizations are a hallmark of early development. Typically developing neonates listen to speech more than many other sounds, including non-biological non-speech sounds, but listen equally to speech and monkey calls. By 3 months of age, however, infants prefer speech over both non-biological non-speech sounds and monkey calls. We examined whether different listening preferences continue to develop along different developmental trajectories and whether listening preferences are related to developmental outcomes. Given the static preference for speech over non-biological non-speech sounds and the dynamic preference for speech over monkey calls between birth and 3 months, we examined whether 9-month-olds prefer speech over non-biological non-speech sounds (Experiment 1) and prefer speech over monkey calls (Experiment 2). We compared preferences for sounds in infants at low risk (SIBS-TD) and infants at high risk (SIBS-A) of autism spectrum disorder (ASD), a heterogeneous population who differ from typically developing infants in their preferences for speech, and examined whether listening preferences predict vocabulary and autism-like behaviors at 12 months for both groups. At 9 months, SIBS-TD listened longer to speech than to non-speech sounds and listened longer to monkey calls than to speech, whereas SIBS-A listened longer to speech than to non-speech sounds but listened equally to speech and monkey calls. SIBS-TD's preferences did not predict immediate developmental outcomes. In contrast, SIBS-A who preferred speech over non-speech or monkey calls had larger vocabularies and fewer markers of autism-like behaviors at 12 months, which could have positive developmental implications.

Language delay aggregates in toddler siblings of children with autism spectrum disorder

BACKGROUND

Language delay is extremely common in children with autism spectrum disorder (ASD), yet it is unclear whether measurable variation in early language is associated with genetic liability for ASD. Assessment of language development in unaffected siblings of children with ASD can inform whether decreased early language ability aggregates with inherited risk for ASD and serves as an ASD endophenotype.

METHODS

We implemented two approaches: (1) a meta-analysis of studies comparing language delay, a categorical indicator of language function, and language scores, a continuous metric, in unaffected toddlers at high and low familial risk for ASD, and (2) a parallel analysis of 350 unaffected 24-month-olds in the Infant Brain Imaging Study (IBIS), a prospective study of infants at high and low familial risk for ASD. An advantage of the former was its detection of group differences from pooled data across unique samples; an advantage of the latter was its sensitivity in quantifying early manifestations of language delay while accounting for covariates within a single large sample.

RESULTS

Meta-analysis showed that high-risk siblings without ASD (HR-noASD) were three to four times more likely to exhibit language delay versus low-risk siblings without ASD (LR-noASD) and had lower mean receptive and expressive language scores. Analyses of IBIS data corroborated that language delay, specifically receptive language delay, was more frequent in the HR-noASD (n = 235) versus LR-noASD group (n = 115). IBIS language scores were continuously and unimodally distributed, with a pathological shift towards decreased language function in HR-noASD siblings. The elevated inherited risk for ASD was associated with lower receptive and expressive language scores when controlling for sociodemographic factors. For receptive but not expressive language, the effect of risk group remained significant even when controlling for nonverbal cognition.

CONCLUSIONS

Greater frequency of language delay and a lower distribution of language scores in high-risk, unaffected toddler-aged siblings support decreased early language ability as an endophenotype for ASD, with a more pronounced effect for receptive versus expressive language. Further characterization of language development is warranted to refine genetic investigations of ASD and to elucidate factors influencing the progression of core autistic traits and related symptoms.

Reduplication facilitates early word segmentation

This study explores the possibility that early word segmentation is aided by infants' tendency to segment words with repeated syllables ('reduplication'). Twenty-four nine-month-olds were familiarized with passages containing one novel reduplicated word and one novel non-reduplicated word. Their central fixation times in response to these as well as new reduplicated and non-reduplicated words introduced at test showed that familiarized reduplicated words were segmented better than familiarized non-reduplicated words. These results demonstrate that infants are predisposed to segment words with repeated phonological elements, and suggest that register-specific words in infant-directed speech may have evolved in response to this learning bias.

Neural responses to linguistic stimuli in children with and without autism spectrum disorder

Atypical neural responses to language have been found in toddlers with autism spectrum disorder (ASD) and in their unaffected siblings. However, given that language difficulties are often seen in these children, it is difficult to interpret whether these neural differences are a result of the diagnosis of ASD or impairments in their language abilities. In this study, we recorded event-related potentials (ERPs) from four groups of 36-month-olds: low-risk control (LRC), high risk for ASD defined as having an older sibling with ASD (HRA) but who do not have ASD or milder autism-like symptoms (HRA-Typ), HRA children who do not have ASD but exhibit milder autism-like symptoms (HRA-Atyp) and HRA children diagnosed with ASD (ASD). Children listened to words expected to be acquired early (e.g. ball) and words expected to be acquired late (e.g. calf). ERPs were analysed over time windows sensitive to word processing as well as frontal and temporo-parietal sites over the left and right hemispheres. When controlling for language abilities, there were group differences within the temporo-parietal sites. Specifically, the HRA-Atyp group showed a different timed response to late words compared to the ASD and LRC groups. In addition, we found a relation between neural responses in the left frontal sites and ASD severity. Our results suggest that both language abilities and ASD diagnoses are important to consider when interpreting neural differences in lexical processing.

The integrity of lexical acquisition mechanisms in autism spectrum disorders: A research review

Research on autism spectrum disorders (ASD) has rapidly expanded in recent years, yielding important developments in both theory and practice. While we have gained important insights into how children with ASD differ from typically developing (TD) children in terms of phenotypic features, less has been learned about if and how development in ASD differs from typical development in terms of underlying mechanisms of change. This article aims to provide a review of processes subserving lexical development in ASD, with the goal of identifying contributing factors to the heterogeneity of language outcomes in ASD. The focus is on available evidence of the integrity or disruption of these mechanisms in ASD, as well as their significance for vocabulary development; topics include early speech perception and preference, speech segmentation, word learning, and category formation. Significant gaps in the literature are identified and future directions are suggested. Autism Res 2016, 9: 810-828. © 2015 International Society for Autism Research, Wiley Periodicals, Inc.

Eye-tracking measurements of language processing: developmental differences in children at high risk for ASD

To explore how being at high risk for autism spectrum disorder (ASD), based on having an older sibling diagnosed with ASD, affects word comprehension and language processing speed, 18-, 24- and 36-month-old children, at high and low risk for ASD were tested in a cross- sectional study, on an eye gaze measure of receptive language that measured how accurately and rapidly the children looked at named target images. There were no significant differences between the high risk ASD group and the low risk control group of 18- and 24-month-olds. However, 36-month-olds in the high risk for ASD group performed significantly worse on the accuracy measure, but not on the speed measure. We propose that the language processing efficiency of the high risk group is not compromised, but other vocabulary acquisition factors might have lead to the high risk 36-month-olds to comprehend significantly fewer nouns on our measure.

Understanding the developing sound system: interactions between sounds and words

Over the course of the first 2 years of life, infants are learning a great deal about the sound system of their native language. Acquiring the sound system requires the infant to learn about sounds and their distributions, sound combinations, and prosodic information, such as syllables, rhythm, and stress. These aspects of the phonological system are being learned simultaneously as the infant experiences the language around him or her. What binds all of the phonological units is the context in which they occur, namely, words. In this review, we explore the development of phonetics and phonology by showcasing the interactive nature of the developing lexicon and sound system with a focus on perception. We first review seminal research in the foundations of phonological development. We then discuss early word recognition and learning followed by a discussion of phonological and lexical representations. We conclude by discussing the interactive nature of lexical and phonological representations and highlight some further directions for exploring the developing sound system. WIREs Cogn Sci 2014, 5:589-602. doi: 10.1002/wcs.1307 For further resources related to this article, please visit the WIREs website.

CONFLICT OF INTEREST

The authors have declared no conflicts of interest for this article.

Autism treatment in the first year of life: a pilot study of infant start, a parent-implemented intervention for symptomatic infants

The goal of early autism screening is earlier treatment. We pilot-tested a 12-week, low-intensity treatment with seven symptomatic infants ages 7-15 months. Parents mastered the intervention and maintained skills after treatment ended. Four comparison groups were matched from a study of infant siblings. The treated group of infants was significantly more symptomatic than most of the comparison groups at 9 months of age but was significantly less symptomatic than the two most affected groups between 18 and 36 months. At 36 months, the treated group had much lower rates of both ASD and DQs under 70 than a similarly symptomatic group who did not enroll in the treatment study. It appears feasible to identify and enroll symptomatic infants in parent-implemented intervention before 12 months, and the pilot study outcomes are promising, but testing the treatment's efficacy awaits a randomized trial.

Event-related potentials to repeated speech in 9-month-old infants at risk for autism spectrum disorder

Background

Atypical neural responses to repeated auditory and linguistic stimuli have been reported both in individuals with autism spectrum disorder (ASD) and their first-degree relatives. Recent work suggests that the younger siblings of children with ASD have atypical event-related potentials (ERPs) to repeated tones at 9 months of age; however, the functional significance is unclear, and it is unknown whether this atypicality is also present in response to linguistic stimuli.

Methods

We analyzed ERPs to repetitive and deviant consonant-vowel stimuli at 9 months in 35 unaffected high-risk-for-autism (HRA) infant siblings of children with ASD and 45 low-risk control (LRC) infants. We examined a positive component, the P150, over frontal and central electrode sites and investigated the relationships between this component and later behavior.

Results

Over frontal electrodes, HRA infants had larger-amplitude ERPs to repetitions of the standard than LRC infants, whereas ERPs to the deviant did not differ between HRA and LRC infants. Furthermore, for HRA infants, the amplitude of ERPs to the standards was positively correlated with later language ability.

Conclusions

Our work suggests that atypical ERPs to repeated speech during infancy are a possible endophenotype of ASD but that this atypicality is associated with beneficial, rather than disordered, language development. Potential mechanisms driving these relationships and implications for development are discussed.