Children in the waitlist control group will receive the same intervention as the intervention group after the waitlist period.

Parents in the waitlist control group will receive an abbreviated version(three-week) of the parent mediated intervention with the same contents as the intervention group.

The Korean Behavior Rating Inventory of Executive Function is a standardized parent report to observe children's cognitive control. It assesses behavior in executive functioning and is used to assess children with learning disabilities and attention disorders, as well as neurological, psychiatric, and medical conditions. It includes 86 items measuring various aspects of each executive function, which are categorized into eight clinical scales and two validity scales to provide a balanced view of the child's behavior. The test is intended for children ages 5-18 and takes approximately 15 minutes to complete.

The Emotion Dysregulation Inventory is an informant questionnaire that assesses emotion regulation difficulties. It consists of 30 items, and informants (parents/caregivers) rate each item (e.g., "has sudden outbursts of emotion," "doesn't seem to enjoy anything") on a 5-point Likert scale ranging from "not at all" to "very severe" based on their observations of the child's functioning over the past 7 days.

Intervention feasibility and acceptability survey will be systematically evaluated using multiple indicators relevant to clinical trial implementation. Intervention feasibility will be assessed by tracking enrollment and retention rates across key demographic characteristics, the proportion of participants deemed ineligible based on screening procedures and clinical assessments, and data acquisition rates for cognitive control-related tasks administered before and after the intervention. Intervention acceptability will be evaluated using Likert-scale ratings and open-ended questions to capture participants' experiences and perceptions of the program (e.g., "Please describe the strengths of the intervention program," "Please describe any difficulties you experienced while participating in the intervention").

The Korean Wechsler Fundamentals: Academic Skills is a brief, standardized achievement assessment adapted and normed from the original Wechsler Fundamentals: Academic Skills (WFA) to evaluate core academic skills essential for learning in educational settings. In the present study, the K-WFA will be used to assess children's academic skill levels and changes associated with intervention effects. The measure evaluates fundamental domains including word reading, reading comprehension, writing, and numerical calculation. The K-WFA consists of parallel forms (Form A and Form B), allowing for pre- and post-intervention assessment, and enables rapid evaluation of functional academic skills as well as monitoring of learning-related changes over time.

The Penn Interactive Peer Play Scale is a play behavior assessment developed to understand children's interactions with peers and to be consistently rated by parents or teachers across settings during early childhood. Our study will utilize the parent report to assess children's play in home and neighborhood environments. The parent report records the level of frequency at which each behavior was observed during the child's free play over a 2-month period. It consists of 32 4-point Likert scales and results include the following domains: play disruption, play interaction, and play disengagement.

The Child Behavior Checklist is a standardized parent-report measure used to assess children's emotional and behavioral problems, with age-specific versions to ensure developmental appropriateness. In this study, it will be administered based on the child's age: the CBCL 1.5-5 will be used for children aged 18 months to 5 years, and the Korean Child Behavior Checklist for Ages 6-18 (K-CBCL 6-18) will be used for children aged 6 to 18 years. The Korean CBCL 1.5-5, published in 2008, includes a Problem Behavior Scale and a Language Development Scale, with the problem behavior items assessing internalizing and externalizing difficulties as well as DSM-oriented symptom domains using a 3-point Likert scale. The K-CBCL 6-18, released in 2010 following nationwide standardization, consists of a 113-item, 3-point Likert-scale Problem Behavior Scale that captures a broad range of emotional and behavioral functioning based on parent report.

The Brief Observation of Social Communication Change is a behavioral observation tool originally developed to measure pre- and post-intervention treatment effects in children with autism. The first 5-6 minutes (Segment A) and the second 5-6 minutes (Segment B) of free play between an interventionist or caregiver and a child with autism are filmed. The number and quality of the child's social communication and interactions (e.g., eye contact, facial expressions, gestures, social cues and responses) and limited and repetitive interests or behaviors (e.g., sensory-seeking behaviors) are observed between 10 and 15 minutes.

We found that EEG central prefrontal theta oscillations, measured using time frequency analysis, provide a new window into understanding the neural basis of cognitive control in children with autism. Children with ASD between ages of 5-6 years showed higher theta power while producing incorrect responses, which require more brain resources than correct responses during go/no-go cognitive tasks. This was correlated with better performance on behavioral cognitive control tasks. In this study, we plan to measure error-related theta oscillations and error-related negativity (ERN) using EEG tasks. We will use the Zoo Game, a validated EEG task that is developmentally appropriate for children. It is a go/no-go task designed to optimize child engagement and motivation by combining animal pictures and an engaging story to make the go and no-go clear and easy for children to understand, and has been shown in previous research to be suitable for children with autism.

The Korean Parenting Stress Index-Fourth Edition Short Form (K-PSI-4-SF) is a parent self-report measure with items extracted from the K-PSI-4 that are most sensitive for measuring parenting stressors. It consists of three subscales (Parental Distress, Parent-Child Dysfunctional Interaction, and Demanding Child) that assess parent characteristics, parent-child interactions, and parent-perceived child characteristics that influence parenting stress, with 12 items per scale. Items are rated on a 5-point Likert scale with varying anchor statements (e.g., from "strongly disagree" (1) to "strongly agree" (5); from "definitely not adequate as a parent" (1) to "a very good parent" (5); and from "much easier than expected" (1) to "much more difficult than expected" (5)). Total scores range from 36 to 180, with higher total scores indicating greater levels of stress experienced in parenting.

The Barkley Deficits in Executive Functioning Scale, which was developed to assess executive function deficits in adult ADHD patients, consists of 89 items with five subdomains: 'Self-management of time', 'Self-organization/problem solving', 'Self-control', 'Self-motivation', and 'Self-regulation of emotions', measured with a 4-point Likert scale. In this study, we will use the Korean version of Short Form (K-BDEFS-SF) to assess the presence of executive function and ADHD symptoms in daily lives of caregivers of children with autism.

This study will use the 10-item Emotion Regulation Questionnaire to measure how parents experience and express their emotions, i.e., how they cognitively interpret and regulate emotion in their daily lives as caregivers. Each item is rated on a 7-point Likert scale from "not at all" to "very much so" (e.g., "When I want to feel more positive, I change the way I think about the situation," "I suppress my emotions.").

The Loneliness and Social Isolation Scale is an instrument that encompasses both objectively measurable "social network" and an individual's subjective perceptions of "social support" and "loneliness" to estimate the complex concept of "social isolation". It consists of 6 questions and is self-reported. Each item is scored on a 0-3 scale.

The UCLA Loneliness Scale was developed by Russell et al. in 1978 and has been the most widely used instrument in loneliness research both domestically and internationally. Based on the definition of Weiss (1973), it defines loneliness as 'a state of extreme distress due to relational deficiency'. The revised version consists of 20 items, such as "I have no one to turn to", and each item is rated on a 4-point Likert scale ranging from "Not at all (1)" to "Often (4)." Higher scores indicate higher levels or frequency of loneliness. This study will use the Korean version of the UCLA Loneliness Scale, which is shortened to 8 items instead of the full 20-item scale.

The Parenting Sense of Competence (PSOC) scale is a parent self-report measure used to assess parenting satisfaction and efficacy. Items are rated on a 6-point Likert scale ranging from "strongly disagree" (1) to "strongly agree" (6), with reverse-scored items included. Higher total scores indicate greater parental efficacy. Scores of 58 or below are interpreted as low, scores between 58 and 74 as average, and scores of 75 or above as high.

The Parent Satisfaction Scale (PSS) is an instrument that assesses caregivers' subjective evaluation of their performance in the parenting role, as well as the positive and negative emotions arising from their parenting experiences. Items are rated on a 4-point Likert scale ranging from "strongly disagree" (1) to "strongly agree" (4), with reverse-scored items included. Higher total scores indicate greater satisfaction with the parenting role.

The Autism Stigma and Knowledge Questionnaire (ASK-Q-2) will be used to assess caregivers' knowledge of and stigma toward autism. Items are scored dichotomously (agree = 1, disagree = 0).

The NISE tests will assess basic learning skills, such as reading and math, for students (ages 5 to 14).