Outcomes of behavioral intervention for children with autism in mainstream pre-school settings

Determining Associations Between Intervention Amount and Outcomes for Young Autistic Children: A Meta-Analysis

Importance

Health professionals routinely recommend intensive interventions (ie, 20-40 hours per week) for autistic children. However, primary research backing this recommendation is sparse and plagued by methodological flaws.

Objective

To examine whether different metrics of intervention amount are associated with intervention effects on any developmental domain for young autistic children.

Data Sources

A large corpus of studies taken from a recent meta-analysis (with a search date of November 2021) of early interventions for autistic children.

Study Selection

Studies were eligible if they reported a quasi-experimental or randomized clinical trial testing the effects of a nonpharmacological intervention on any outcome in participant samples comprising more than 50% autistic children 8 years or younger.

Data Extraction and Synthesis

Data were independently extracted by multiple coders. Meta-regression models were constructed to determine whether each index of intervention amount was associated with effect sizes for each intervention type, while controlling for outcome domain, outcome proximity, age of participants, study design, and risk of detection bias. Data were analyzed from June 2023 to February 2024. This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Main Outcomes and Measures

The primary predictor of interest was intervention amount, quantified using 3 different metrics (daily intensity, duration, and cumulative intensity). The primary outcomes of interest were gains in any developmental domain, quantified by Hedges g effect sizes.

Results

A total of 144 studies including 9038 children (mean [SD] age, 49.3 [17.2] months; mean [SD] percent males, 82.6% [12.7%]) were included in this analysis. None of the meta-regression models evidenced a significant, positive association between any index of intervention amount and intervention effect size when considered within intervention type.

Conclusions and Relevance

Findings of this meta-analysis do not support the assertion that intervention effects increase with increasing amounts of intervention. Health professionals recommending interventions should be advised that there is little robust evidence supporting the provision of intensive intervention.

Development and Preliminary Validation of the Patient Outcome Planning Calculator (POP-C): A Tool for Determining Treatment Dosage in Applied Behavior Analysis

Board certified behavior analysts (BCBA) are responsible for determining the medically necessary treatment dosage for patients (i.e., the number of hours of therapy a patient should receive per week to optimize progress) during applied behavior analysis (ABA) therapy. However, because there is currently no standard method for making these determinations, BCBAs must rely on their own clinical judgment. Given that clinical judgment may be underdeveloped in some BCBAs, particularly those who are newly certified, more formal strategies are needed to guide decision making as it relates to medical necessity and treatment dosage. In this article we describe the development of the Patient Outcome Planning Calculator (POP-C), a standardized decision-making tool designed to assist novice practitioners in determining the medically necessary ABA treatment intensity and appropriate treatment setting for individuals with autism spectrum disorder (ASD). We present preliminary reliability data as well as construct validity data indicating statistically significant correlations between the POP-C and several norm-referenced and criterion-referenced assessments commonly used to estimate skill level and the corresponding degree of support needed within the ASD population to inform the ABA treatment model and goals.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40617-023-00861-6.

Evaluation of the Integrated Therapy Model in Preschool Education for Children with Autism Spectrum Disorder in China

The Integrated Therapy Model is a practice framework designed to promote multi-disciplinary collaboration to accommodate the holistic needs of children with special education needs. This study evaluated the effectiveness of the model adopted in a pilot preschool in China on children with autism spectrum disorder (ASD). A single-case, ABAB reversal design was employed with three children with ASD, and data were collected using direct observation and semi-structured interviews. The results demonstrated that while the model piloted in China was effective at improving fine motor ability, gross motor ability, imitation and problem behavior, it had mild to questionable effects on self-care and independent living capacity. The implications for the practice and for research on preschool interventions in mainland China is discussed.

Adapting the preschool environment to the needs of children on the autism spectrum in Sweden: A quasi-experimental study

BACKGROUND

Children on the autism spectrum may receive Early Intensive Behavioural Intervention (EIBI) in Sweden to support development by providing learning opportunities. However, research suggests a need to improve the quality of their learning environment.

AIM

This pre-registered study (#NCT03634761) aimed to evaluate the Swedish Autism Program Environment Rating Scale (APERS-P-SE) as a means to promote the quality of the pre-school learning environment for children on the autism spectrum, along with outcomes for these children, and their pre-school staff.

MATERIAL AND METHODS

In a quasi-experimental study, pre-school staff (n = 35) conducted either EIBI supported by in-service training and on-site coaching based on APERS-P-SE assessment (at k = 9 preschools) or EIBI only (k = 8), during an 8-months period.

RESULTS

The quality of the immediate learning environment (primary outcome) increased significantly in the EIBI/APERS-P-SE preschools. However, changes in child and pre-school staff measures were not significant.

CONCLUSIONS AND SIGNIFICANCE

In-service training and on-site coaching based on APERS-P-SE assessments can increase the quality of the learning environment in Swedish pre-school. Studies of longer duration and larger sample size are required to determine if using the APERS-P-SE can also achieve desired behavioural change for children-, and impact pre-school staff applying EIBI.

Competency drivers to support implementation of early intensive behavioral intervention in large-scale community-based services: Perspectives of caseworkers and organization representatives

Implementing evidence-based practices in "real-world" settings poses significant challenges. Organizations involved must address this issue by providing supportive infrastructures. Among the elements to consider are competency drivers, which refer to the selection, training, and supervision of caseworkers. The purpose of this study was to describe the perspectives of caseworkers and representatives on competency drivers that organizations put in place to support the implementation of early intensive behavioral intervention (EIBI) in large-scale community-based services. The sample consisted of 109 caseworkers and 23 organization representatives who completed questionnaires. Results demonstrated that respondents consider clinical support and training as key elements in EIBI implementation. However, despite recognizing these factors, respondents reported considerable variability in practices. It appears necessary to better define and plan the implementation of these competency drivers with a view to improving EIBI implementation.

Comprehensive ABA-based interventions in the treatment of children with autism spectrum disorder - a meta-analysis

BACKGROUND

Many studies display promising results for interventions that are based on Applied Behavior Analysis (ABA) in the treatment of autism spectrum disorder (ASD).

METHODS

This meta-analysis assessed the effects of such treatments on developmental outcomes in children with ASD and on parental stress based on 11 studies with 632 participants.

RESULTS

Compared to treatment as usual, minimal or no treatment, comprehensive ABA-based interventions showed medium effects for intellectual functioning (standardized mean difference SMD = 0.51, 95% CI [0.09; 0.92]) and adaptive behavior (SMD = 0.37, 95% CI [0.03; 0.70]). Language abilities, symptom severity or parental stress did not improve beyond the improvement in control groups. Moderator analyses indicate that language abilities at intake could influence the effect sizes and the influence of treatment intensity might decrease with older age.

CONCLUSIONS

Practical implications and limitations are discussed.

Examining Predictors of Different ABA Treatments: A Systematic Review

In the recent literature, there is a broad consensus on the effectiveness of Applied Behavior Analysis interventions for autism spectrum disorder (ASD). Despite their proven efficacy, research in clinical settings shows that these treatments are not equally effective for all children and the issue of which intervention should be chosen for an individual remains a common dilemma. The current work systematically reviewed studies on predictors and moderators of response to different types of evidence-based treatment for children with ASD. Specifically, our goal was to critically review the relationships between pre-treatment child characteristics and specific treatment outcomes, covering different aspects of functioning (i.e., social, communicative, adaptive, cognitive, motor, global functioning, play, and symptom severity). Our results questioned the binomial “better functioning-better outcome”, emphasizing the complex interplay between pre-treatment child characteristics and treatment outcomes. However, some pre-treatment variables seem to act as prerequisites for a specific treatment, and the issue of “what works for whom and why” remains challenging. Future research should focus on the definition of evidence-based decision-making models that capture those individual factors through which a specific intervention will exert its effects.

Concordance between patient-centered and adaptive behavior outcome measures after applied behavior analysis for autism

BACKGROUND

Applied behavior analysis (ABA) is an evidence-based approach to autism spectrum disorder that has been shown in clinical trials to improve child functional status. There is substantial focus in ABA on setting and tracking individualized goals that are patient-centered, but limited research on how to measure progress on such patient-centered outcomes.

PURPOSE

The purpose of this investigation was to assess concordance between patient-centered and standard outcome measures of treatment progress in a real-world clinical sample of children receiving ABA for autism spectrum disorder.

METHODS

This observational study used a clinical sample of children ages 3 to 16 years (N = 154) who received 24 months of ABA from an integrated health system. Concordance between three outcome measures after ABA was assessed using a correlation matrix: (1) patient-centered measures of progress on individualized treatment goals, (2) caregiver-centered measure of progress on treatment participation goals, and (3) the Vineland Adaptive Behavior Scales adaptive behavior composite.

RESULTS

There was limited concordance among measures at both 12 and 24 months of ABA. None of the patient-centered measures showed significant positive correlation with adaptive behavior composite difference scores at either 12 or 24 months, nor did the caregiver measure. The percentage of children achieving clinically meaningful gain on patient-centered goal measures increased between 12 and 24 months of ABA, while the percentage of children achieving clinically meaningful gains in adaptive behavior declined during the same time period.

CONCLUSIONS

In a health system implementation of ABA, there was limited concordance between patient-centered and standard measures of clinically meaningful treatment progress for children with ASD. Clinicians should have ongoing dialogue with patients and parents/caregivers to ensure that interventions for ASD are resulting in progress towards outcomes that are meaningful to patients and families.

Analysis of a Statewide Early Intervention Program for Young Children with ASD

We evaluated the effectiveness of a statewide Medicaid program providing in-home Early Intensive Behavioral Intervention services to young children with Autism Spectrum Disorder living in a rural southern state. Program effectiveness was assessed via the Assessment of Basic Language and Learning Skills-Revised (ABLLS-R). A multi-level growth model was used to show significant variation among children's initial ABLLS-R scores and their growth trajectories. Hispanic children tended to have lower initial scores but demonstrated similar growth compared to their non-Hispanic peers. Children who were older at initial start in the program appeared to have higher initial composite scores and higher growth trajectories. Children in more populous counties had higher initial scores but grew at similar rates to children in more rural counties.

Pre-symptomatic intervention for autism spectrum disorder (ASD): defining a research agenda

Autism spectrum disorder (ASD) impacts an individual's ability to socialize, communicate, and interact with, and adapt to, the environment. Over the last two decades, research has focused on early identification of ASD with significant progress being made in understanding the early behavioral and biological markers that precede a diagnosis, providing a catalyst for pre-symptomatic identification and intervention. Evidence from preclinical trials suggest that intervention prior to the onset of ASD symptoms may yield more improved developmental outcomes, and clinical studies suggest that the earlier intervention is administered, the better the outcomes. This article brings together a multidisciplinary group of experts to develop a conceptual framework for behavioral intervention, during the pre-symptomatic period prior to the consolidation of symptoms into diagnosis, in infants at very-high-likelihood for developing ASD (VHL-ASD). The overarching goals of this paper are to promote the development of new intervention approaches, empirical research, and policy efforts aimed at VHL-ASD infants during the pre-symptomatic period (i.e., prior to the consolidation of the defining features of ASD).

From Someone Who May Cause Trouble to Someone You Can Play With: Stakeholders' Perspectives on Preschool Program Quality for Autistic Children

In Sweden, young autistic children typically attend community-based preschool programs, which may not be adapted to their needs. In the current study, stakeholders to autistic children receiving Early Intensive Behavioral Intervention were interviewed following a quasi-randomized study (#NCT03634761) aimed at improving the preschool program quality using the Swedish version of the Autism Program Environment Rating Scale (APERS). Stakeholders provided their perceptions and experiences concerning key factors for high quality preschool programs as well as well as their experiences of the abovementioned APERS study. Applying thematic analysis, stakeholder groups differed in what they emphasized, but all highlighted staff’s competence, children’s inclusion and participation, collaboration, and the learning environment as key program areas that had been positively influenced by the APERS-based intervention.

Behavior analytic interventions for children with autism: Policy and practice in the United Kingdom and China

LAY ABSTRACT

The prevalence of autism is increasing, and the development of these children and the lived experience of their families have become a global concern. Applied behavioral analytic intervention is proved to be effective in improving their cognitive abilities, language skills, and social and emotional skills, but the service delivery between developed and developing countries is different. A qualitative study was conducted to explore personal experiences with actual practice fidelity of behavior analytic services for children with autism in a Western developed country (United Kingdom) and an Eastern developing country (China). The study found: (1) a lack of support for autism and behavioral analytic services in both countries; (2) applied behavioral analytic intervention was not as widely endorsed by healthcare or educational systems in the United Kingdom; Chinese parents faced challenges around inclusive education and accessing high-quality services and there was a social stigma attached to autism; (3) a limited awareness and application of early intensive behavior intervention in both regions; and (4) intervention fidelity with regards to the practice of one particular aspect of behavioral analytic interventions was similar and increased with ongoing training. This study emphasizes the need to support children with autism, and to consider regional adaptations of evidence-based practice of behavior analytic interventions for the affected population.

Unsupervised Machine Learning for Identifying Challenging Behavior Profiles to Explore Cluster-Based Treatment Efficacy in Children With Autism Spectrum Disorder: Retrospective Data Analysis Study

Background

Challenging behaviors are prevalent among individuals with autism spectrum disorder; however, research exploring the impact of challenging behaviors on treatment response is lacking.

Objective

The purpose of this study was to identify types of autism spectrum disorder based on engagement in different challenging behaviors and evaluate differences in treatment response between groups.

Methods

Retrospective data on challenging behaviors and treatment progress for 854 children with autism spectrum disorder were analyzed. Participants were clustered based on 8 observed challenging behaviors using k means, and multiple linear regression was performed to test interactions between skill mastery and treatment hours, cluster assignment, and gender.

Results

Seven clusters were identified, which demonstrated a single dominant challenging behavior. For some clusters, significant differences in treatment response were found. Specifically, a cluster characterized by low levels of stereotypy was found to have significantly higher levels of skill mastery than clusters characterized by self-injurious behavior and aggression (P<.003).

Conclusions

These findings have implications on the treatment of individuals with autism spectrum disorder. Self-injurious behavior and aggression were prevalent among participants with the worst treatment response, thus interventions targeting these challenging behaviors may be worth prioritizing. Furthermore, the use of unsupervised machine learning models to identify types of autism spectrum disorder shows promise.

The Importance of Professional Discourse for the Continual Advancement of Practice Standards: The RBT® as a Case in Point

The Behavior Analyst Certification Board (BACB®) created a third level of certification, the Registered Behavior Technician™ (RBT®) in 2014. The RBT® was created based upon the requests of stakeholders who wanted to credential those individuals who make direct contact with clients under the supervision of a Board Certified Behavior Analyst®. There has been tremendous growth in the number of RBTs® with over 60,000 individuals certified to date. The BACB® recently sent out a newsletter outlining changes to the RBT® certification, including the processes of training, supervising, and becoming an RBT®. These changes represent a number of potential concerns. The purpose of this paper is to highlight these concerns and to propose solutions to improve the RBT® certification.

Intensive behavioural interventions based on applied behaviour analysis for young children with autism: An international collaborative individual participant data meta-analysis

LAY ABSTRACT

Early intensive applied behaviour analysis-based interventions are designed to support young autistic children's learning and development. Unfortunately, the available evidence about the effectiveness of these interventions remains unclear. Several reviews have focused on the published findings rather than contacting the authors to collect and analyse data about the individual participants in the original studies. Also, most of the studies were carried out by groups involved in delivering the interventions leading to the potential bias in interpreting the results. Our research team (supported by an international advisory group) carried out an independent individual patient data review by collecting the original participant data from the authors of the studies, to examine the effectiveness of these interventions. The results suggested that early intensive applied behaviour analysis-based interventions might lead to some changes in children's cognitive ability (intelligence quotient) and everyday life skills after 2 years, compared with standard treatments. However, all the studies had problems with the way they were designed. Also, few of the studies looked at outcomes that have been described as most important to autistic people or followed children beyond 2 years. We think that further systematic reviews of the existing evidence are unlikely to add to the findings of our review. Furthermore, we recommend that future research should investigate which types of supports and interventions are most effective for children and families, prioritising outcomes measures that are meaningful for the autism community and include, wherever possible, longer-term follow-up.

Dog training intervention improves adaptive social communication skills in young children with autism spectrum disorder: A controlled crossover study

LAY ABSTRACT

There is some evidence that using therapy dogs for children with autism spectrum disorder generally results in improved social communication skills and reduced behavioral problems. However, well-controlled studies that examine its effectiveness are scarce. This study examined the effectiveness of a "Dog Training Intervention." The study included 73 participants diagnosed with autism spectrum disorder (61 males, 12 females) with age range of 2:10-7:6 years (M = 4:10 ± 1:0) who attend autism spectrum disorder-specific special education schools. The study population was divided into two groups. Each group received the dog training intervention during one part of the school year (first half or second half) in addition to the standard interventions provided by the special education school settings. The dog training intervention was given twice weekly for 4 months within the school setting. The group that received the dog training intervention first showed a significant increase in adaptive social and communication skills in comparison to the second group that did not receive the intervention in this period. This improvement was maintained after the dog training intervention. The second group, which received intervention at the second half of the year, showed improvement in communication and socialization adaptive skills only during the period in which they received the dog training intervention. The positive impact on social communication adaptive skills of the dog training intervention among young children with autism spectrum disorder suggests that dogs may serve as an effective model for establishing social interaction. Dog training intervention appears to be an effective adjunct treatment to the interventions provided in special education schools for young children with autism spectrum disorder.

A SWOT analysis of parent-mediated intervention for children with autism spectrum disorder: Oman as a Regional Model

The prevalence of autism in the Arabian Gulf region is on the rise leading to overstretching of the pre-existing intervention services. The World Health Organization Caregiver Skills Training Program is a novel renovation being studied around the globe to overcome the scarcity of resources, improve autistic children's outcome and empower parents with comparable results to therapist-based models. Recently, Oman achieved great success in advocating for autism and initiated the first screening program for autism in the region. This review aims to use a Strength, Weakness, Opportunities and Threats (SWOT) analysis matrix to investigate the potential for using a parent-mediated intervention program as a supplementary approach to the currently used therapist-based intervention model in the country as an example for Gulf region.

An evaluation of a comprehensive training package for interventionists providing behavioral intervention for children with autism spectrum disorder

There has been rapid growth in the number of behavior analysts and interventionists in the world today. With this growth it is imperative to ensure that each behavior analyst and interventionist receives quality training. The training should be comprehensive (i.e. training multiple areas of behavior analysis) and should not conclude until the trainee is able to perform each behavior analytic procedure to a high degree of fidelity. The purpose of this study was to evaluate the effectiveness of a training package to train four participants how to implement multiple behavior analytic procedures. Using a multiple baseline design across participants the results indicate that each participant improved their implementation of behavioral intervention. Additionally, the participants maintained their skills over time.

Interventions based on early intensive applied behaviour analysis for autistic children: a systematic review and cost-effectiveness analysis

BACKGROUND

Early intensive applied behaviour analysis-based interventions are intensive interventions for autistic children that are often delivered on a one-to-one basis for 20-50 hours per week.

OBJECTIVES

To evaluate the clinical effectiveness and cost-effectiveness of early intensive applied behaviour analysis-based interventions for autistic children, based on current evidence.

METHODS

A systematic review and individual participant data meta-analysis were conducted to evaluate the clinical effectiveness of an early intensive applied behaviour analysis-based intervention for autistic children. An economic analysis included a review of existing analyses and the development of a new model.

RESULTS

Twenty studies were included in the clinical review. Individual participant data were retrieved from 15 of these studies. Results favoured the interventions when assessing adaptive behaviour after 2 years compared with treatment as usual/eclectic interventions (mean difference 7.00, 95% confidence interval 1.95 to 12.06). In analyses of cognitive ability (intelligence quotient), results favoured the interventions by approximately 10 points after 1 year (mean difference 9.16, 95% confidence interval 4.38 to 13.93) and 2 years (mean difference 14.13, 95% confidence interval 9.16 to 19.10). Evidence for other outcomes was limited and meta-analyses were generally inconclusive. There was no evidence that the effect of the interventions varied with characteristics of the children, but data were limited. Adopting a £30,000 per quality-adjusted life-year threshold, the results of the cost-effectiveness analysis indicate that early intensive applied behaviour analysis-based interventions would need to generate larger benefits or cost savings to be cost-effective. Adopting a public sector perspective and making pessimistic assumptions about long-term effects, the incremental cost-effectiveness ratio for early intensive applied behaviour analysis-based therapy compared with treatment as usual is £189,122 per quality-adjusted life-year. When optimistic assumptions are made, the incremental cost-effectiveness ratio is £46,768 per quality-adjusted life-year. Scenario analyses indicated that these interventions can potentially be cost-effective if long-term improvements persist into adulthood, or if they have significant impact on educational placement. Care should be taken when interpreting these scenarios owing to the limited data.

LIMITATIONS

All included studies were at risk of bias, there was substantial heterogeneity and effects varied considerably across studies. The effect of intervention on autism symptom severity, language development and school placement remains uncertain because of the limited data. The long-term effects are unclear owing to a lack of follow-up data.

CONCLUSIONS

This review found limited evidence that early intensive applied behaviour analysis-based interventions may improve cognitive ability and adaptive behaviour, but the long-term impact of the interventions remains unknown. The economic analysis is constrained by the limited effectiveness evidence, but suggests that these interventions are unlikely to be cost-effective unless clear long-term benefits, or a substantial change in which schools children attend, can be identified.

FUTURE WORK

Further studies into the effectiveness of early intensive applied behaviour analysis-based interventions may be warranted if they include well-defined, alternative interventions as comparators and collect relevant outcomes. Consideration should be given to future studies that not only address whether or not early intensive applied behaviour analysis-based interventions are clinically effective, but also aim to identify which components of early intensive applied behaviour analysis-based interventions might drive effectiveness.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42017068303.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 24, No. 35. See the NIHR Journals Library website for further project information.

Intervention Effects on Language in Children With Autism: A Project AIM Meta-Analysis

Purpose This study synthesized effects of interventions on language outcomes of young children (ages 0-8 years) with autism and evaluated the extent to which summary effects varied by intervention, participant, and outcome characteristics. Method A subset of effect sizes gathered for a larger meta-analysis (the Autism Intervention Meta-analysis or Project AIM) examining the effects of interventions for young children with autism, which were specific to language outcomes, was analyzed. Robust variance estimation and metaregression were used to calculate summary and moderated effects while controlling for intercorrelation among outcomes within studies. Results A total of 221 outcomes were gathered from 60 studies. The summary effect of intervention on language outcomes was small but significant. Summary effects were larger for expressive and composite language outcomes compared to receptive language outcomes. Interventions implemented by clinicians, or by clinicians and caregivers together, had summary effects that were significantly larger than interventions implemented by caregivers alone. Participants' pretreatment language age equivalent scores positively and significantly moderated intervention effects, such that effects were significantly larger on average when samples of children had higher pretreatment language levels. Effects were not moderated by cumulative intervention intensity, intervention type, autism symptomatology, chronological age, or the proximity or boundedness of outcomes. Study quality concerns were apparent for a majority of included outcomes. Conclusions We found evidence that intervention can facilitate improvements in language outcomes for young children with autism. Effects were largest for expressive and composite language outcomes, for children with initially higher language abilities, and for interventions implemented by clinicians or by caregivers and clinicians combined. However, quality concerns of included studies and borderline significance of some results temper our conclusions regarding intervention effectiveness and corresponding moderators.

Intervention Effects on Language in Children With Autism: A Project AIM Meta-Analysis

Purpose This study synthesized effects of interventions on language outcomes of young children (ages 0-8 years) with autism and evaluated the extent to which summary effects varied by intervention, participant, and outcome characteristics. Method A subset of effect sizes gathered for a larger meta-analysis (the Autism Intervention Meta-analysis or Project AIM) examining the effects of interventions for young children with autism, which were specific to language outcomes, was analyzed. Robust variance estimation and metaregression were used to calculate summary and moderated effects while controlling for intercorrelation among outcomes within studies. Results A total of 221 outcomes were gathered from 60 studies. The summary effect of intervention on language outcomes was small but significant. Summary effects were larger for expressive and composite language outcomes compared to receptive language outcomes. Interventions implemented by clinicians, or by clinicians and caregivers together, had summary effects that were significantly larger than interventions implemented by caregivers alone. Participants' pretreatment language age equivalent scores positively and significantly moderated intervention effects, such that effects were significantly larger on average when samples of children had higher pretreatment language levels. Effects were not moderated by cumulative intervention intensity, intervention type, autism symptomatology, chronological age, or the proximity or boundedness of outcomes. Study quality concerns were apparent for a majority of included outcomes. Conclusions We found evidence that intervention can facilitate improvements in language outcomes for young children with autism. Effects were largest for expressive and composite language outcomes, for children with initially higher language abilities, and for interventions implemented by clinicians or by caregivers and clinicians combined. However, quality concerns of included studies and borderline significance of some results temper our conclusions regarding intervention effectiveness and corresponding moderators.

Quality of Early Intensive Behavioral Intervention as a Predictor of Children's Outcome

Research has directed surprisingly little attention to the quality of Early Intensive Behavioral Intervention (EIBI) in autism spectrum disorder (ASD) as a potential predictor of outcome. Therefore, using a preschool delivery model within a sample of 30 children, we examined the predictive power of EIBI quality on treatment outcome. EIBI quality was assessed at baseline by the York Measure of Quality of Intensive Behavioral Intervention (YMQI) and treatment outcome was evaluated after a period of 4 to 6 months using a battery of behavioral tests and scales to evaluate treatment success. Multinomial logistic regressions demonstrated that general EIBI quality predicted clinically significant change at follow-up. Particularly improvements in basic language and learning skills and global clinical impression were observed. Specific quality indicators that influenced overall treatment success were treatment organization, teaching level and differential reinforcement. In addition to previously examined predictors of EIBI treatment effects, such as child characteristics and intervention quantity, our findings highlight the importance of adequate EIBI quality assurance.

Changes in Developmental Trajectories of Preschool Children with Autism Spectrum Disorder during Parental Based Intensive Intervention

Background: Research highlights the positive effects of early intensive intervention with parent and school involvement for preschool children with Autism Spectrum Disorder (ASD) on general developmental outcomes and social skills in randomized controlled trials. However, given the inter-individual variability in the response to treatment, it is necessary to investigate intervention effects in terms of mediators and moderators in order to explain variability and to highlight mechanisms of change. Methods: 25 children in the experimental group were exposed to early intensive intervention and 14 children in the control group were subjected to “as usual” intervention. The initial assessment was obtained at the time of diagnosis (T1) and the follow-up assessment was conducted after 15 months of intervention (T2) in both groups. Results: Participants in the experimental group achieved more prominent gains in both cognitive and socio-interactive skills. The role of specific factors able to predict general quotient and language quotient after intervention were investigated, pointing out the contribution of personal–social and performance abilities. Conclusions: The findings support the importance of parental involvement in targeting ASD core symptoms. Further, results informed our understanding of early predictors in order to identify specific elements to be targeted in the individualized intervention design.

Project AIM: Autism intervention meta-analysis for studies of young children

In this comprehensive systematic review and meta-analysis of group design studies of nonpharmacological early interventions designed for young children with autism spectrum disorder (ASD), we report summary effects across 7 early intervention types (behavioral, developmental, naturalistic developmental behavioral intervention [NDBI], TEACCH, sensory-based, animal-assisted, and technology-based), and 15 outcome categories indexing core and related ASD symptoms. A total of 1,615 effect sizes were gathered from 130 independent participant samples. A total of 6,240 participants, who ranged in age from 0-8 years, are represented across the studies. We synthesized effects within intervention and outcome type using a robust variance estimation approach to account for the nesting of effect sizes within studies. We also tracked study quality indicators, and report an additional set of summary effect sizes that restrict included studies to those meeting prespecified quality indicators. Finally, we conducted moderator analyses to evaluate whether summary effects across intervention types were larger for proximal as compared with distal effects, and for context-bound as compared to generalized effects. We found that when study quality indicators were not taken into account, significant positive effects were found for behavioral, developmental, and NDBI intervention types. When effect size estimation was limited to studies with randomized controlled trial (RCT) designs, evidence of positive summary effects existed only for developmental and NDBI intervention types. This was also the case when outcomes measured by parent report were excluded. Finally, when effect estimation was limited to RCT designs and to outcomes for which there was no risk of detection bias, no intervention types showed significant effects on any outcome. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Neighbourhood-level prevalence of teacher-reported Autism Spectrum Disorder among kindergarten children in Canada: A population level study

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Number of children with ASD per neighbourhood varies from none to as high as 21.

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Developmental vulnerabilities were not associated with levels of clustering.

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Highest level of clustering of children with ASD was found in Nova Scotia.

Seeking Team Collaboration, Dialogue and Support: The Perceptions of Multidisciplinary Staff-Members Working in ASD Preschools

Autism spectrum disorder (ASD) impacts various developmental domains, requiring interventions by professionals from multiple disciplines. In Israel, ASD community preschools' multidisciplinary teams aim to provide each child with an integrative intervention program. The current study focused on the working experience of 21 professionals from multidisciplinary teams in ASD-preschools, with special emphasis on their perceptions of the intra-staff dialogue in their teams. Interviews were transcribed verbatim and analyzed through grounded theory. Arising themes covered: challenges characterizing the delivery of intervention to children with ASD in a community setting; challenges met by professionals when attempting to navigate multidisciplinary teamwork; and factors that facilitate multidisciplinary work. Practices that support multidisciplinary team cohesion at the team, the organizational, and the policy-making levels are discussed.

Cross-Cultural Content Validity of the Autism Program Environment Rating Scale in Sweden

Increasing rates of autism spectrum disorder (ASD) and younger age at diagnosis pose a challenge to preschool intervention systems. In Sweden, most young autistic children receive intervention service in community-based preschool programs, but no tool is yet available to assess the quality of the preschool learning environment. This study adapted the Autism Program Environment Rating Scale Preschool/Elementary to Swedish community context (APERS-P-SE). Following translation and a multistep modification process, independent experts rated the content validity of the adaptation. Findings indicate high cross-cultural validity of the adapted APERS-P-SE. The cultural adaption process of the APERS-P-SE highlights similarities and differences between the American and Swedish preschool systems and their impact on early ASD intervention.

Effectiveness of Training Therapists to Deliver An Individualized Mental Health Intervention for Children With ASD in Publicly Funded Mental Health Services: A Cluster Randomized Clinical Trial

IMPORTANCE

Publicly funded mental health services play an important role in addressing co-occurring mental health problems in children with autism spectrum disorder (ASD); however, therapists report lacking training to effectively serve this complex population.

OBJECTIVE

To test the effectiveness of training community therapists in An Individualized Mental Health Intervention for ASD (AIM HI) on challenging behaviors across 18 months among children with ASD and identify moderators and mediators of any intervention effects.

DESIGN, SETTING, AND PARTICIPANTS

Cluster randomized trial conducted in 29 publicly funded outpatient and school-based mental health programs in southern California from 2012 to 2017. Programs were randomized to receive immediate AIM HI training or provide usual care followed by receipt of AIM HI training. Therapist participants were recruited from enrolled programs, and child participants were recruited from participant therapists' caseloads. Data were analyzed from 202 children with ASD who were aged 5 to 13 years.

INTERVENTIONS

The AIM HI protocol is a package of parent-mediated and child-focused strategies aimed to reduce challenging behaviors in children with ASD who are 5 to 13 years old. It was designed for delivery in publicly funded mental health services based on a systematic assessment of therapist training needs and child clinical needs. The therapist training and consultation process takes approximately 6 months and includes an introductory workshop, 11 structured consultation meetings as the therapist delivers AIM HI with a current client, and case-specific performance feedback from trainers.

MAIN OUTCOMES AND MEASURES

Child participants were assessed for challenging behaviors using the Eyberg Child Behavior Inventory (ECBI) and Social Skills Improvement System (SSIS) Competing Problem Behaviors scales based on parent report at baseline and at 6-month intervals for 18 months. Outcomes were analyzed using intent-to-treat models.

RESULTS

In total, 202 children with ASD (mean [SD] age, 9.1 [2.4] years; 170 [84.2%] male; 121 [59.9%] Latinx) were eligible, enrolled, and included in the analyses. Statistically significant group by time interactions for the ECBI Intensity (B = -0.38; P = .02) and ECBI Problem (B = -1.00; P = .005) scales were observed, with significantly larger decreases in ECBI Intensity scores in the AIM HI group (B = -1.36; P < .001) relative to the usual care group (B = -0.98; P < .001) and a significantly larger decrease in ECBI Problem scores in the AIM HI group (B = -1.22; P < .001) relative to the usual care group (B = -0.20; P = .29). Therapist fidelity moderated these intervention effects.

CONCLUSIONS AND RELEVANCE

The present findings support the effectiveness of training therapists to deliver the AIM HI model to children with ASD receiving publicly funded mental health services.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02416323.

Toddlers to teenagers: Long-term follow-up study of outcomes in autism spectrum disorder

This prospective study examined the developmental changes over time of adolescents diagnosed in toddlerhood with autism spectrum disorder and searched for child characteristics at toddlerhood that predict outcome at adolescence. The study included 65 participants who were divided into low cognitive (developmental quotient < 85; N = 41) and high cognitive (developmental quotient ⩾ 85; N = 21) groups in adolescence. Participants underwent a comprehensive assessment of cognitive ability, adaptive skills, and autism severity. Significant differences in the current clinical phenotypes and in developmental changes over time were found between the two cognitive groups. At baseline, the high cognitive group had significantly less severe social communication deficits. Only the high cognitive group showed a decrease in social communication deficits over time. Although the two groups did not differ in their adaptive skills at the time of diagnosis, the high cognitive group had better adaptive skills at adolescence. Better adaptive communication skills in toddlerhood were associated with better outcome at adolescence in cognitive ability, adaptive skills, and fewer autism symptoms. Less impaired baseline social affect and better cognitive ability predicted higher cognitive level and adaptive skills at adolescence. Cognitive potential of individuals with autism spectrum disorder plays an important role in long-term outcome and comprehensive evaluations at toddlerhood have strong prognostic value in adolescence.

Speech therapy intervention in a teenager with autism spectrum disorder: a case report

ABSTRACT Autism Spectrum Disorder is a neurodevelopmental disorder that affects socio-communicative and behavioral abilities. In the language aspect, there is a greater impairment at the pragmatic level and in non-verbal aspects. The objective of this study was to characterize the severity of Autism Spectrum Disorder in an adolescent, pre-and post-speech-language therapy, and describe the process of speech-language intervention using Picture Exchange Communication System allied to the principles of behavioral analysis applied to language. The Autism Treatment Evaluation Checklist with the parents was applied. Then, a therapeutic program of 14 sessions of 50 minutes was developed, one per week, and then the questionnaire was reapplied. In the course of the therapeutic process, it was possible to observe an increase in the number of figure exchanges independently, an increase in the number of vocalizations with communicative intention or functional speech, longer time of visual contact and social smile, reduction of inappropriate behaviors with a significant improvement in the Autism Treatment Evaluation Checklist score.

Moderate Effects of Low-Intensity Behavioral Intervention

We compared clinical outcomes in a treatment group of 98 individuals who received between 8 and 15 weekly hours (M = 10.6; SD = 1.7) of applied behavior analysis (ABA) intervention with a comparison group of 73 individuals who received another provision, including some ABA, (between 1.4-8 weekly hours, M = 5.7; SD = 1.6). After 2 years, the treatment group made greater gains than the comparison group on language and social skills, and other areas assessed by the Verbal Behavior Milestones Assessment and Placement Program (VB-MAPP). We evaluated the outcome on adaptive skills for a smaller sample of participants using the Vineland Adaptive Behavior Scales II (VABS), but found no significant differences between the treatment (n = 17) and comparison groups (n = 11). Although the treatment group made important and clinically meaningful gains, the gains were moderate. These findings underline the importance of intervention intensity and provide further support for a dose-response relationship between ABA intervention hours and outcomes.

Follow-Up of Children With Autism Spectrum Disorder 1 Year After Early Behavioral Intervention

The effectiveness of early intensive behavioral intervention (EIBI) for children with autism spectrum disorders (ASDs) has been demonstrated by many studies and meta-analyses. Although it is considered an exemplary practice in several countries, few studies have investigated the maintenance of gains made in EIBI over time. Thirty-two children were assessed at posttreatment and 1-year follow-up after they attended a low-to-moderate-intensity (10 to 20 hr per week) EIBI program delivered by a public rehabilitation center. Between baseline and posttreatment, children showed significant gains in most areas of intellectual functioning and a significant decrease of autism symptom severity, but no change in adaptive behavior. Gains in intellectual functioning were maintained over a 1-year period after treatment termination, but autism symptom severity had increased to approximately pretreatment levels during that interval. Considerable individual variability was noted in the evolution of outcomes.

The effect of caregiver-delivered social-communication interventions on skill generalization and maintenance in ASD

BACKGROUND

Although caregiver-delivered social communication interventions have been considered scientifically proven practices for individuals with autism spectrum disorders, it is not well examined if these types of intervention modes are truly effective in promoting skill generalization and maintenance within those individuals with autism spectrum disorders.

AIMS

The purpose of this meta-analysis was to evaluate the status of the extant literature regarding the measures on generalization and/or maintenance of effects of caregiver-delivered communication interventions for children with autism spectrum disorders.

METHODS AND PROCEDURES

This systematic literature review and meta-analysis evaluated peer-reviewed research regarding the effects of caregiver-implemented interventions on the maintenance and generalization of the social-communication skills for children with autism spectrum disorders. A total of 34 articles were included following a systematic search. Articles were summarized according to the following categories: (a) generalization dimension, (b) generalization assessment design, (c) maintenance assessment design, (d) generalization/maintenance teaching strategy, and (e) latency to maintenance probes. After application of design standards, aggregate Tau-U and non-overlap of pairs effect sizes were calculated with a total of 67 separate contrasts across seven studies.

OUTCOMES AND RESULTS

Overall, effect size scores ranged from small to large effects across all comparisons. On average, most of the baseline to maintenance and generalization comparisons produced moderate to large effects. Whereas, small to moderate or even deteriorate effects were found in most of the intervention to maintenance and generalization comparisons.

CONCLUSIONS AND IMPLICATIONS

The findings in this review suggest that caregiver-delivered social-communication interventions are likely to result in mixed effects on skill generalization and maintenance within children with autism spectrum disorders. Implications for future research and practice are discussed.

Efficacy of early interventions for infants and young children with, and at risk for, autism spectrum disorders

With advances in the field's ability to identify autism spectrum disorders (ASD) at younger ages, the need for information about the evidence-base for early intervention continues to rise. This review of the ASD early intervention (EI) literature focuses on efficacy studies published within the past 15 years. The neurodevelopmental context for early intervention, timing of initiating intervention, primary intervention approaches, and predictors of treatment outcomes are discussed. The evidence indicates that young children with ASD benefit from EI, and their parents learn to implement child-responsive engagement strategies when a parent-coaching intervention is provided. Evidence supports combining parent-mediated and direct clinician-implemented intervention to maximize child developmental gains. Clinical practice recommendations are presented, based on the literature reviewed.

Allegiance and knowledge levels of professionals working with early intensive behavioural intervention in autism

AIM

Early intensive behavioural intervention (EIBI) for children with autism spectrum disorder (ASD) is often delivered using a community model. Behaviour modification experts train and supervise non-experts (e.g. preschool personnel) to teach children according to applied behaviour analysis principles in their natural environment. Several factors predict EIBI outcomes in ASD, for example, knowledge of EIBI and EIBI allegiance among trainers. The aim of the present study was to survey levels of knowledge about and allegiance towards EIBI.

METHODS

Formal knowledge of EIBI and EIBI allegiance was surveyed in supervised preschool staff conducting EIBI (n = 33), preschool staff not involved in EIBI (n = 26), behaviour modification experts (n = 60), school staff (n = 25) and parents of children with ASD (n = 150) [N = 294]. A 27-item (15 knowledge and 12 allegiance questions) online questionnaire was collected.

RESULTS

Supervised preschool staff conducting EIBI had more knowledge than preschool staff not using EIBI, but they were not more allegiant. Compared with behaviour modification experts, the supervised EIBI preschool staff group showed markedly less knowledge and allegiance.

CONCLUSIONS

Findings indicate potential for improvement regarding formal knowledge levels of preschool staff delivering EIBI to children with ASD in real-world settings. In addition, fostering EIBI allegiance might be prioritized when teaching EIBI among non-experts. Broadly increased EIBI knowledge levels among all preschool teachers should be achieved by adding behaviour modification techniques to common university curricula in preschool education. Allegiance of preschool personnel might be accomplished by EIBI supervisors meeting skepticism in practice with conveyance of evidence-based principles and discussions of ethical issues.

Cross-Cultural Validation of the York Measure of Quality of Intensive Behavioral Intervention

Early intensive behavioral intervention (EIBI) is widely applied in young children with autism spectrum disorder. Little research has addressed the significance of adherence to EIBI practices for treatment outcomes. The York Measure of Quality of Intensive Behavioral Intervention (YMQI) was designed to assess EIBI quality delivery in Ontario, Canada. The objective of this study was to examine the cross-cultural validity of the YMQI in a clinical Swedish community sample of 30 boys and four girls with autism aged 2.5 to 6 years. Internal consistency was alpha = .87 for the full scale YMQI. Interrater reliability among three raters on 97 video-recorded therapy sequences was .71 (intraclass correlation coefficient [ICC]), and intrarater reliability of two raters re-scoring 15 sequences after 6 months was ICC = .87. The convergent validity of the YMQI with EIBI expert ratings was r = .49. Findings endorse the psychometric properties of the YMQI and its usability outside of Anglo-Saxon countries.

Le point de vue de parents d’enfants présentant un trouble du spectre de l’autisme en regard d’un programme public d’intervention comportementale

L’intervention comportementale intensive (ICI) est implantée depuis 2003 dans les services publics québécois destinés aux enfants de 2 à 5 ans ayant un trouble du spectre de l’autisme. Ce choix a été fait sur la base de l’avis d’experts et des données probantes à l’effet que l’ICI représente l’intervention la plus efficace pour les jeunes enfants ayant ce type de trouble. Bien que les effets de l’ICI soient largement documentés, la perception des familles quant aux services d’ICI reçus demeure peu étudiée. À partir d’entretiens effectués auprès de 52 familles, le point de vue des parents concernant les services d’ICI a été abordé selon trois dimensions : l’appréciation générale, les effets perçus sur l’enfant et la famille ainsi que le niveau de satisfaction. Les données ont été recueillies à partir de questions ouvertes, d’un questionnaire structuré et de l’Échelle de satisfaction des services (CSQ-8). Les parents participants rapportent que l’équipe d’intervention, les modalités d’intervention ainsi que le contenu de l’intervention des services ICI sont les principaux points forts des services évalués. Des améliorations pourraient néanmoins être apportées à certaines modalités de dispensation des services, ainsi qu’à l’accessibilité, aux mouvements de personnel et à l’implication des parents. Tous les parents, sauf un, rapportent des effets positifs chez l’enfant, notamment sur les plans de la communication, du fonctionnement cognitif et des aspects sociaux. Les services ont aussi des effets sur le bien-être des parents, leurs habiletés parentales et la vie quotidienne familiale. Plus de 95 % des répondants se sont déclarés satisfaits ou très satisfaits des modalités du programme ICI. Le niveau général de satisfaction est également très élevé.

Implementation of early intensive behavioural intervention for children with autism in Switzerland

BACKGROUND

There is a major gap between the US and most European countries regarding the implementation of early intensive behavioural intervention (EIBI) for children with autism. The present paper reports on the current status of EIBI in Switzerland and on the effectiveness of EIBI under clinical conditions in a Swiss pilot project.

METHODS

The paper combines a narrative report of the care system for children with autism in Switzerland and an initial evaluation of EIBI as implemented in the Department of Child and Adolescent Psychiatry, University of Zurich.

RESULTS

The current situation of the implementation of EIBI for children with autism in Switzerland is characterized by marked deficits in its acceptance. Major reasons include insufficient governmental approval and lacking legal and financial support. In addition, ignorance among health care providers and educational professionals has contributed to this situation precluding that children with autism receive the most beneficial assistance. The authors have initiated and been working in an intervention centre offering EIBI for a decade and report on their experience with the implementation of EIBI. Based on their clinical practice, they document that EIBI also works efficiently under ordinary mental health service conditions.

CONCLUSIONS

EIBI needs to be implemented more intensively in Switzerland. Although the effects of EIBI as implemented in Zurich are promising, the results are not as pronounced as under controlled research conditions.

Determinants of developmental progress in pre-schoolers referred for neuro-developmental diagnosis

AIM

To determine factors associated with change in developmental progress in pre-schoolers referred to a developmental clinic.

METHODS

Of 360 pre-schoolers referred to a Child Assessment clinic for neuro-developmental diagnosis before 3.6 years, 190 (53%) were reassessed prior to school entry and recruited to this study. They were assessed with the Bayley Scales of Infant and Toddler Development (3rd edn) before 3.5 years and the Griffiths Mental Development Scales before school entry. The influence of medical and environmental variables on improvement or deterioration in scores (±0.5 SD) was examined using logistic regression.

RESULTS

Consistent scores were present in 51.6% of children, and associated with environmental variables. Children with stable scores were more likely to live in a suburb of social advantage (OR = 3.2; 95%CI = 1.37-7.64, P = 0.008) or to come from families dependent on welfare or public housing (OR=4.8; 95%CI = 2.19-10.49, P < 0.001). Improvement was seen in 18.1% of children; they were more likely to have commenced therapy after the first assessment (OR = 2.4; 95%CI = 1.05-5.58, P = 0.038). Deterioration of scores was seen in 30% of children. Children with a mild delay on initial assessment were less likely to deteriorate (OR = 2.9; 95%CI = 1.16-7.04, P = 0.022), while lower scores were more likely in children with neuro-motor disabilities (OR = 10.8; 95%CI = 2.64-44.58, P < 0.001), and chromosomal variations of both known and unknown significance (OR = 4.4; 95%CI = 1.54-12.76, P = 0.006).

CONCLUSIONS

Socio-economic advantage and disadvantage are associated with stable scores, but introducing intervention is associated with improved scores. Deterioration is most likely in children with chromosomal variations or neuro-motor disabilities, and regular reassessment of these children is recommended.

Utilisation of evidence-based practices by ASD early intervention service providers

A number of autism intervention practices have been demonstrated to be effective. However, the use of unsupported practices persists in community early intervention settings. Recent research has suggested that personal, professional and workplace factors may influence intervention choices. The aim of this research was to investigate knowledge and use of strategies, organisational culture, individual attitudes, sources of information and considerations informing intervention choices by early intervention providers. An online survey was completed by 72 early intervention providers from four organisations across Australia. Providers reported high levels of trust and access of information from internal professional development, therapists and external professional development. A range of considerations including child factors, family values and research were rated as important in informing intervention choices. Participants reported greater knowledge and use of evidence-based and emerging practices than unsupported. Levels of use were linked to levels of knowledge, as well as some organisational and attitudinal factors. Areas for future research and implications are discussed.

An Evaluation of the Impact of Supervision Intensity, Supervisor Qualifications, and Caseload on Outcomes in the Treatment of Autism Spectrum Disorder

Ample research has shown the benefits of intensive applied behavior analysis (ABA) treatment for autism spectrum disorder (ASD); research that investigates the role of treatment supervision, however, is limited. The present study examined the relationship between mastery of learning objectives and supervision hours, supervisor credentials, years of experience, and caseload in a large sample of children with ASD (N = 638). These data were retrieved from a large archival database of children with ASD receiving community-based ABA services. When analyzed together via a multiple linear regression, supervision hours and treatment hours accounted for only slightly more of the observed variance (r² = 0.34) than treatment hours alone (r² = 0.32), indicating that increased supervision hours do not dramatically increase the number of mastered learning objectives. In additional regression analyses, supervisor credentials were found to have a significant impact on the number of mastered learning objectives, wherein those receiving supervision from a Board Certified Behavior Analyst (BCBA) mastered significantly more learning objectives. Likewise, the years of experience as a clinical supervisor showed a small but significant impact on the mastery of learning objectives. A supervisor's caseload, however, was not a significant predictor of the number of learning objectives mastered. These findings provide guidance for best practice recommendations.

Ensino de linguagem receptiva para crianças com autismo : comparando dois procedimentos

Este trabalho comparou a eficiência de um treino de Discriminação Simples-Condicional (DSC), que empregou blocos de tentativas e três estímulos desde o seu início, com a do treino de Discriminação Condicional (DC), no ensino de linguagem receptiva para três crianças com autismo. Com cada criança foram treinadas nove relações palavra falada-figura em cada tipo de treino. O treino DSC consistiu na redução gradual de tentativas por bloco (de seis blocos de três tentativas, na Fase 1 para nove blocos de duas tentativas, na Fase 2), até sua randomização total, na Fase 3. O treino DC foi idêntico à Fase 3 de DSC, porém com outros estímulos. O treino DC se mostrou mais eficiente para o estabelecimento da linguagem receptiva, mas o treino DSC foi mais efetivo para a manutenção do repertório. Discutem-se as implicações desses resultados para a área aplicada e direções para novos estudos.