A Bayesian statistics tutorial for clinical research: Prior distributions and meaningful results for small clinical samples.

OBJECTIVES: Bayesian statistics provides an effective, reliable approach for research with small clinical samples and yields clinically meaningful results that can bridge research and practice. This tutorial demonstrates how Bayesian statistics can be effectively and reliably implemented with a small, heterogeneous participant sample to promote reproducible and clinically relevant research. METHODS/RESULTS: We tested example research questions pertaining to language and clinical features in autism spectrum disorder (ASD; n = 20), a condition characterized by significant heterogeneity. We provide step-by-step instructions and visualizations detailing how to (1) identify and develop prior distributions from the literature base, (2) evaluate model convergence and reliability, and (3) compare models with different prior distributions to select the best performing model. Moreover, in step three, we demonstrate how to determine whether a sample size is sufficient for reliably interpreting model results. We also provide instructions detailing how to examine results with varied bounds of clinical interest, such as the probability that an effect will reflect at least one standard deviation change in scores on a standardized assessment. This information facilitates generalization and application of Bayesian results to a variety of clinical research questions and settings. CONCLUSION: The tutorial concludes with suggestions for future clinical research, ensuring the utility of our step-by-step instructions for a broad clinical audience.

Preschool language variation, growth, and predictors in children on the autism spectrum.

BACKGROUND: There is wide variation in language abilities among young children with autism spectrum disorders (ASD), with some toddlers developing age-appropriate language while others remain minimally verbal after age 5. Conflicting findings exist regarding predictors of language outcomes in ASD and various methodological issues limit the conclusions that can be drawn about factors associated with positive language growth that could provide insights into more effective intervention approaches for increasing communication skills. METHODS: Language development was investigated in 129 children with ASD participating in four assessments from mean age 2½ years (Visit 1) through 5½ years (Visit 4). Language ability was measured by a clinician-administered test of comprehension and production. Hierarchical linear modeling was used to identify predictors of language ability. Stability of language status was examined in subgroups of Preverbal versus Verbal children identified at Visit 1. Discriminant function analysis was used to classify another subset of cases according to Low Language (minimally verbal) versus High Language outcome at Visit 4. RESULTS: ASD severity was a significant predictor of growth in both language comprehension and production during the preschool period, while cognition predicted growth in production. For the highest and lowest language performers at Visit 4, cognition, maternal education, and response to joint attention correctly classified over 80% of total cases. The vast majority of children who were preverbal at 2½ years attained some level of verbal skills by 5½ years. CONCLUSIONS: Findings indicate that it is possible, by 2½ years, to predict language growth for children with ASD across the preschool years and identify factors that discriminate between children who remain minimally verbal at 5½ years from those with high language proficiency. Results suggest that early intervention focused on reducing core ASD symptoms may also be important for facilitating language development in young children with ASD.

Social and Linguistic Correlates of Vocabulary Size in Autism: Overlapping Vocalization and Phonological Memory.

This study sought to understand the wide variability in vocabulary development among autistic children by testing potential social and linguistic correlates of vocabulary size. The correlation between overlapping vocalization (i.e., an aspect of social interaction relevant to accessing input for vocabulary acquisition) and phonological memory (i.e., retaining linguistic sound sequences) with vocabulary size were examined in 22 autistic children (3 to 11 years old) engaged in a structured nonword repetition task. Overlapping vocalization and phonological memory were correlated with vocabulary size. Overlapping vocalization remained a significant predictor of receptive and expressive vocabulary size when controlling phonological memory and nonverbal cognition. Both social and linguistic factors were associated with receptive and expressive vocabulary size in autistic children engaged in a structured task.

The Work Ahead for Intellectual and Developmental Disabilities Research.

In "Toward Equity in Research on Intellectual and Developmental Disabilities," we sought to make entrenched assumptions and practices of intellectual and developmental disabilities research visible by explicitly describing the status quo in terms of models of disability, participant and researcher identities, research priorities, and biases in measurement and treatment approaches. We then curated individual- and systems-level actions drawn from disability justice and broader social justice lenses to offer a way forward. We focused on three major areas (i.e., intersectionality and person-centered approaches, participatory research, and interprofessional collaboration), depicting influences, methods, and actions in a framework of disability, identity, and culture. In this Author Response, we address five commentaries that critique and extend that synthesis.

Toward Equity in Research on Intellectual and Developmental Disabilities.

Lack of diversity in IDD research is typically conceptualized only in terms of (1) recruitment of samples that do not appropriately represent the sociodemographics of the population, or (2) the limited number of researchers from historically marginalized backgrounds. Critically, the field also suffers from over-reliance on perspectives and social systems of dominant culture-both in how disability is regarded and in relation to other dimensions of identity and culture. These lenses lead to research findings that reinforce, rather than reduce, social inequities. We propose a framework that minimizes reliance on diagnostic categories, shifts from deficit- to person-centered models, acknowledges people's multiple identities, and includes self-advocates and diverse communities as partners in the research enterprise. The systems change necessary to support this framework is described.

Parental scaffolding in play: A comparison of fetal alcohol spectrum disorders and autism spectrum disorder.

BACKGROUND: Parental support of child play varies based on child needs; however, how parental play level differs from child play level remains an understudied area of research, especially in relation to specific developmental disabilities. AIMS: To preliminarily explore differences in child and parent play levels in age- and IQ-matched children with fetal alcohol spectrum disorders (FASD) and autism spectrum disorder (ASD). METHODS: and Procedures: Parent-child dyads were recorded during free-play sessions. Parent/child play levels were coded for highest level achieved during each minute of play. Mean play level and dPlay (difference in parent versus child play level) were calculated across play sessions for each dyad. OUTCOMES AND RESULTS: On average, parents of children with FASD demonstrated higher levels of play than other parents. Children with FASD demonstrated higher levels of play than their own parents. In contrast, the play level of parents of children with ASD did not differ from their child's. There were no between-group differences in dPlay. CONCLUSIONS AND IMPLICATIONS: This preliminary exploratory study suggests that parents of children with developmental disabilities may differentially 'match' their child's play level. Further research on developmental play levels during parent-child play is warranted.

Consistency and reliability of automated language measures across expressive language samples in autism.

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder with substantial clinical heterogeneity, especially in language and communication ability. There is a need for validated language outcome measures that show sensitivity to true change for this population. We used Natural Language Processing to analyze expressive language transcripts of 64 highly-verbal children and young adults (age: 6-23 years, mean 12.8 years; 78.1% male) with ASD to examine the validity across language sampling context and test-retest reliability of six previously validated Automated Language Measures (ALMs), including Mean Length of Utterance in Morphemes, Number of Distinct Word Roots, C-units per minute, unintelligible proportion, um rate, and repetition proportion. Three expressive language samples were collected at baseline and again 4 weeks later. These samples comprised interview tasks from the Autism Diagnostic Observation Schedule (ADOS-2) Modules 3 and 4, a conversation task, and a narration task. The influence of language sampling context on each ALM was estimated using either generalized linear mixed-effects models or generalized linear models, adjusted for age, sex, and IQ. The 4 weeks test-retest reliability was evaluated using Lin's Concordance Correlation Coefficient (CCC). The three different sampling contexts were associated with significantly (P < 0.001) different distributions for each ALM. With one exception (repetition proportion), ALMs also showed good test-retest reliability (median CCC: 0.73-0.88) when measured within the same context. Taken in conjunction with our previous work establishing their construct validity, this study demonstrates further critical psychometric properties of ALMs and their promising potential as language outcome measures for ASD research.

[Formula: see text]Parental interaction style, child engagement, and emerging executive function in fetal alcohol spectrum disorders (FASD).

Children with fetal alcohol spectrum disorders (FASD) are known to experience cognitive and neurobehavioral difficulties, including in areas of executive function and social skills development. Interventions for these challenges have focused on a number of areas, including parent-based training. Despite the general consensus that specific parenting styles consistent with an "authoritative" - warm but firm - parenting approach may influence behavioral self-regulation, it is not known what specific parental interaction styles are associated with child engagement and emerging executive function in this population. The current study used an observation-based behavioral coding scheme during parent-child play interactions and associated parent report-based executive function measures in children with FASD. Here, we demonstrate that parental interaction styles with increased responsive/child-oriented behavior and parental affect are associated with higher levels of child play engagement, while parental interaction that has increased achievement-orientation is associated with higher levels of emerging executive function in children with FASD. These findings help inform future studies on behavioral targets in parent-based training programs and highlight the importance of considering certain parental interaction styles during parent-child play.

Analysis of a Repetitive Language Coding System: Comparisons between Fragile X Syndrome, Autism, and Down Syndrome.

Expressive language sampling (ELS) is a frequently used tool for language analysis, as it can be used across widely ranging cognitive and language abilities. ELS can also evaluate pragmatic language, including excessive self-repetition, which is challenging to assess with traditional standardized assessments. This study explored how a well-established ELS protocol can assess three types of linguistic self-repetition in three neurodevelopmental disabilities: fragile X syndrome (FXS), autism spectrum disorder (ASD), and Down syndrome (DS). We examined its ability to differentiate between these disorders, the relationships between repetitive language and other participant characteristics, and initial construct validity. We found that the groups with FXS and ASD differed significantly on each of the three repetitive language measure, and that the group with DS differed from either ASD or FXS on two. Cognitive ability was significantly related to phrase repetition in the group with ASD. When the groups were combined, there was evidence of convergent and divergent validity. This study extends previous research on ELS and supports its use as a means to characterize pragmatic language. It also provides information about the relationships between repetitive language and other phenotypic characteristics.

Relationship Between Task-Based and Parent Report-Based Measures of Attention and Executive Function in Children with Fetal Alcohol Spectrum Disorders (FASD).

A majority of children with fetal alcohol spectrum disorders (FASD) have demonstrated attention and executive function deficits as measured by both parent report measures and performance on tasks requiring sustained levels of attention. However, prior studies have consistently reported a lack of association between parental report-based and task-based performance measures. The current study investigated whether changes in performance over time within-task (i.e., first-half versus second-half) better correspond to parental reports of executive function and temperament in children with FASD. Greater differences in split-half performance during a continuous performance task were found to be associated with higher parent-reported levels of behavioral regulation and inhibitory control. These findings suggest that within-task performance differences may more accurately reflect individual differences in executive function and temperament as measured by parental report and help to further inform the way in which cognitive processes are measured in children with FASD.

Expressive language development in adolescents with Down syndrome and fragile X syndrome: change over time and the role of family-related factors.

BACKGROUND: It is well known that individuals with Down syndrome (DS) or fragile X syndrome (FXS) demonstrate expressive language difficulties beginning early in childhood. It is less clear, however, whether expressive language skills change during the adolescent period in these individuals, and if any of these changes are syndrome specific. Studying this, as well as the role of maternal and family-related factors in expressive language development, may provide the foundation for efficacious interventions for adolescents with DS or FXS. METHODS: In this study, we examined expressive language trajectories, assessed through conversation and narration, in 57 adolescent males with intellectual disability (ID) (20 DS and 37 FXS) in relation to the diagnostic group (DS vs. FXS) and family-related factors (maternal IQ, maternal psychological distress, closeness in the mother-child relationship, family income, and maternal and paternal education) after adjusting for chronological age (CA) and nonverbal cognition. RESULTS: Changes over repeated annual assessments for males with DS or FXS were observed only during conversation, such as an increase in talkativeness, but a decrease in syntax complexity and lexical diversity. We found a diagnosis-related effect in the change over time in conversational talkativeness favoring those with FXS. Finally, a closer mother-child relationship predicted less decrease over time in lexical diversity during conversation, and participants of mothers who graduated college showed a greater increase in conversational talkativeness over time compared to those of mothers with a high school education. CONCLUSIONS: Our results suggest that, during the adolescent period for males with DS or FXS, there is an increase in the amount of talk produced in conversational contexts, but also a decrease in the quality of the language produced. In addition, our results indicate syndrome-specificity for aspects of expressive language development and reinforce the protective role of family-related factors.

Syntactic Ability of Girls With Fragile X Syndrome: Phonological Memory and Discourse Demands on Complex Sentence Use.

This study was designed to establish the extent of delay in complex sentence use by females with fragile X syndrome (FXS) and to identify sources of variability among individuals. Females with FXS (n = 16; 10;2-15;7) and younger typically developing girls (n = 17; 4;1-8;11) were group-wise matched on nonverbal cognition and receptive syntax. Language samples (conversation and narration) yielded syntactic complexity in terms of mean length of C-unit (MLCU) and Developmental Level sentence coding (DLevel; Rosenberg & Abbeduto, 1987 ). Complex syntax was not weaker than developmental expectations; however, MLCU was lower than expected for age. Phonological memory and verbal working memory correlated with measures of syntactic complexity in narration. Discourse demands may play an important role in the language produced by females with FXS.

The relation between parent verbal responsiveness and child communication in young children with or at risk for autism spectrum disorder: A systematic review and meta-analysis.

Among preschool-age children with autism spectrum disorder (ASD) and typically developing children, parents' verbal responsiveness (PVR) has long been shown to predict children's later language ability. However, before the age of three, when language develops most rapidly, the early social communication deficits associated with ASD may impact parents' opportunities to facilitate early language development. The aim of this review was to characterize the relation between PVR and the vocal communication ability of children with or at high risk for ASD early in development. Specifically, we examined whether the relation between PVR and child communication varied by type of PVR and by child diagnostic status, as well as whether interventions increased PVR. A systematic multi-database search yielded 25 empirical studies (804 parent-toddler dyads; 30 effect sizes) that met inclusion criteria and related a variable of PVR to a variable of child vocalization or language. Meta-regression analyses revealed that the relation between PVR and child communication was significant regardless of PVR type or child diagnostic status. To date, interventions targeting both PVR and child communication were found to significantly increase PVR, but not child communication, for these populations. Future research should examine parent-child communication in a transactional, longitudinal manner. In addition, these findings have implications for interventions designed to target parents' responsiveness and child communication. Autism Research 2019, 12: 715-731. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: For families with children under 3 years old who are at risk for or diagnosed with ASD, this study revealed empirical evidence of a robust relation between parents'' verbal responsiveness to their children's play and communication and children's communication ability. This relation is similar to that reported in research on typically developing children. Interventions designed to improve parent-child interaction in children with or at risk for ASD may be effective in increasing parents' responsiveness.

Signaling noncomprehension of language: a comparison of fragile X syndrome and Down syndrome.

Signaling noncomprehension of the spoken messages of others was examined for youth with fragile X or Down syndrome in comparison with each other and nonverbal MA-matched typically developing children. A direction-following task was used in which some of the directions were inadequate. Both syndrome groups signaled noncomprehension less often than did the typically developing children. The ability to signal noncomprehension appropriately was related to a measure of receptive vocabulary and syntax. Preliminary analyses indicated that males with fragile X syndrome signaled noncomprehension less often than did their female peers, even after controlling for differences in nonverbal MA.

Distributional Cues to Language Learning in Children With Intellectual Disabilities.

Purpose: In typical development, distributional cues-patterns in input-are related to language acquisition processes. Statistical and implicit learning refer to the utilization of such cues. In children with intellectual disability, much less is known about the extent to which distributional cues are harnessed in mechanisms of language learning. Method: This tutorial presents what is known about the process of language learning in children with language impairments associated with different sources of intellectual disability: Williams syndrome, autism spectrum disorder, Down syndrome, and fragile X syndrome. Results: A broad view is taken on distributional cues relevant to language learning, including statistical learning (e.g., transitional probabilities) and other patterns that support lexical acquisition (e.g., sensitivities to sound patterns, cross-situational word learning) or relate to syntactic development (e.g., nonadjacent dependencies). Conclusions: Critical gaps in the literature are highlighted. Research in this area is especially limited for Down syndrome and fragile X syndrome. Future directions for taking learning theories into account in interventions for children with intellectual disability are discussed, with a focus on the importance of language input.

Auditory-visual misalignment: A theoretical perspective on vocabulary delays in children with ASD.

In this commentary, we describe a novel theoretical perspective on vocabulary delays in children with autism spectrum disorder (ASD)-a perspective we refer to as auditory-visual misalignment. We synthesize empirical evidence that: (a) as a result of differences in both social and nonsocial visual attention, the auditory-visual statistics available to children with ASD for early word learning are misaligned; (b) this auditory-visual misalignment disrupts word learning and contributes to the vocabulary delays shown by children with ASD; and (c) adopting a perspective of auditory-visual misalignment has important theoretical and clinical implications for understanding and supporting vocabulary development in children with ASD. Theoretically, the auditory-visual misalignment perspective advances our understanding of how attentional differences impact vocabulary development in children with ASD in several ways. By adopting the point of view of the child, we provide a framework that brings together research on social and domain-general visual attention differences in children with ASD. In addition, the auditory-visual misalignment perspective moves current thinking beyond how misalignment disrupts vocabulary development in the moment, and considers the likely consequences of misalignment over developmental time. Finally, considering auditory-visual misalignment may assist in identifying active ingredients of existing language interventions or in developing new interventions that deliver high quality, aligned input. Future research is needed to determine how manipulating auditory-visual alignment changes word learning in ASD and whether the effects of auditory-visual misalignment are unique to ASD or shared with other neurodevelopmental disorders or sources of language impairment. Autism Research 2018, 11: 1621-1628. © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: This article describes a new way of thinking about vocabulary delays in children with autism spectrum disorder (ASD). We suggest that children with ASD may have difficulty learning words because their attention is not tuned in to what is most important for learning, creating a mismatch between what they see and what they hear. This perspective brings together research on different types of attentional differences in people with ASD. It may also help us to understand how language interventions work.

The Shape Bias in Children With Autism Spectrum Disorder: Potential Sources of Individual Differences.

Purpose: Children with autism spectrum disorder (ASD) demonstrate many mechanisms of lexical acquisition that support language in typical development; however, 1 notable exception is the shape bias. The bases of these children's difficulties with the shape bias are not well understood, and the current study explored potential sources of individual differences from the perspectives of both attentional and conceptual accounts of the shape bias. Method: Shape bias performance from the dataset of Potrzeba, Fein, and Naigles (2015) was analyzed, including 33 children with typical development (M = 20 months; SD = 1.6), 15 children with ASD with high verbal abilities (M = 33 months; SD = 4.6), and 14 children with ASD with low verbal abilities (M = 33 months; SD = 6.6). Lexical predictors (shape-side noun percentage from the MacArthur-Bates Communicative Development Inventory; Fenson et al., 2007) and social-pragmatic predictors (joint attention duration during play sessions) were considered as predictors of subsequent shape bias performance. Results: For children in the low verbal ASD group, initiation of joint attention (positively) and passive attention (negatively) predicted subsequent shape bias performance, controlling for initial language and developmental level. Proportion of child's known nouns with shape-defined properties correlated negatively with shape bias performance in the high verbal ASD group but did not reach significance in regression models. Conclusions: These findings suggest that no single account sufficiently explains the observed individual differences in shape bias performance in children with ASD. Nonetheless, these findings break new ground in highlighting the role of social communicative interactions as integral to understanding specific language outcomes (i.e., the shape bias) in children with ASD, especially those with low verbal abilities, and point to new hypotheses concerning the linguistic content of these interactions. Presentation Video: https://doi.org/10.23641/asha.7299581.

A longitudinal assessment of executive function skills and their association with math performance.

The present study was designed to examine both concurrent and predictive associations between scores on a measure of executive function (EF) skills, the Contingency Naming Test (CNT), during the early school-age years. A secondary aim of the study was to examine the association between EF skills and mathematics performance. We administered tests of mathematics ability, and the CNT, to 178 children at ages 6 to 7, 8 to 9, and 10 to 11 years. From the CNT we obtained measures of response fluency/efficiency, working memory, and inhibition. The results demonstrate main effects of age on all CNT measures of EF, as anticipated, and inconsistent main effects of gender or mathematics learning disability status. Rates of improvement in EF varied as a function of the working memory demands present during a given task. There were differences in concurrent and predictive correlations for different CNT performance measures. EF scores obtained during the first assessment were as strongly associated with each other as they were with EF scores obtained four years later, suggesting a moderately stable source of individual differences on cognitive performance. EF scores at age 6 to 7 years were associated with concurrent and later mathematics scores, and most of these correlations were stronger than the significant associations found between response fluency on a baseline task (with no working memory demand) and mathematics performance. These findings have implications for the stability of EF skills during the school-age years, and the role of EF in early and later elementary school mathematics performance.

Noncomprehension Signaling in Males and Females With Fragile X Syndrome.

Purpose: This study used a prospective longitudinal design to evaluate the trajectory and predictors of noncomprehension signaling in male and female youth with fragile X syndrome (FXS). Method: A direction-following task in which some of the directions were inadequate was administered. Participants were 52 youth (36 boys, 16 girls) with FXS. Upon study entry, participants ranged from 10 to 16 years. The average number of annual assessments per participant was 3.65 (range = 1-4), providing 198 data points for analysis. Results: Participants with FXS were less likely to signal noncomprehension than younger, typically developing, cognitively matched children. The average rate of change in noncomprehension signaling was not significantly different from 0 for either boys or girls, suggesting a plateau. Both FMRP and nonverbal IQ were significant independent predictors of noncomprehension signaling for boys. Variability in noncomprehension signaling among girls was not explained by any of the predictors, but trends similar to those observed for boys were observed. Conclusions: Noncomprehension signaling appears to be an area of weakness for individuals with FXS. Because the failure to signal noncomprehension can have negative, cumulative effects on comprehension, the results suggest a need for interventions targeting the requisite cognitive skills.

The effect of methylphenidate-OROS® on the narrative ability of children with attention-deficit hyperactivity disorder.

BACKGROUND AND OBJECTIVE: Children with attention-deficit hyperactivity disorder (ADHD) experience difficulty with expressive language, including form (e.g. grammatical construction) and content (e.g. coherence). The current study aimed to investigate the effect of methylphenidate-Osmotic Release Oral System® (MPH-OROS®) on the narrative ability of children with ADHD and language impairment, through the analysis of microstructure and macrostructure narrative elements. METHOD: In a single group off-on medication test design, narratives were obtained from 12 children with ADHD, aged 7-13 years, using wordless picture books. For microstructure, number of words, type-token ratio and mean length of utterance were derived from narrative samples using Systematic Analysis of Language Transcripts conventions. For macrostructure, the narratives were coded according to the Narrative Scoring Scheme, which includes seven narrative characteristics, as well as a composite score reflecting the child's overall narrative ability. RESULTS: The administration of MPH-OROS® resulted in a significant difference in certain aspects of language macrostructure: cohesion and overall narrative ability. Little effect was noted in microstructure elements. CONCLUSION: We observed a positive effect of stimulant medication on the macrostructure, but not on the microstructure, of narrative production. Although stimulant medication improves attention and concentration, it does not improve all aspects of language abilities in children with ADHD. Language difficulties associated with ADHD related to language content and use may be more responsive to stimulant medication than language form, which is likely to be affected by cascading effects of inattention, hyperactivity and impulsivity beginning very early in life and to progress over a more protracted period. Therefore, a combination of treatments is advocated to ensure that children with ADHD are successful in reaching their full potential.