This study set up two experiments using the free viewing video paradigm. By setting up social threat scenarios induced by humans (Experiment 1) and non social threat scenarios induced by objects (Experiment 2), combined with eye tracking and fNIRS technology, we explored the eye movement patterns and related brain activation characteristics of IJA in children with ASD.

Inclusion Criteria:

-

For ASD group:

1. 3 years ≤ age ≤ 10 years;
2. a diagnosis of autism spectrum disorder based on clinical symptoms, confirmed using the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) and other auxiliary diagnostic scales, including the Autism Diagnostic Interview-Revised (ADI-R) and the Childhood Autism Rating Scale (CARS);
3. further confirmation of ASD symptoms by experimenters with established research reliability using the Autism Diagnostic Observation Schedule, Second Edition (ADOS-2), with severity scores reported;
4. absence of comorbid physical diseases or other psychiatric disorders, including normal vision (or corrected-to-normal vision) and normal hearing;
5. no receipt of medication, transcranial magnetic stimulation (TMS), or transcranial direct current stimulation (tDCS) within the past three months.

For TD group:The inclusion criterion for the TD group was a score below the cutoff on the Social Responsiveness Scale (SRS).

Exclusion Criteria:

-

For ASD group:

1. age < 3 years or > 10 years;
2. absence of a diagnosis of autism spectrum disorder based on the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) and other auxiliary diagnostic scales, including the Autism Diagnostic Interview-Revised (ADI-R) and the Childhood Autism Rating Scale (CARS);
3. failure to meet diagnostic criteria after confirmation of ASD symptoms by experimenters with established research reliability using the Autism Diagnostic Observation Schedule, Second Edition (ADOS-2);
4. presence of comorbid physical diseases or other psychiatric disorders, or problems with vision (or corrected-to-normal vision) and hearing;
5. receipt of medication, transcranial magnetic stimulation (TMS), or transcranial direct current stimulation (tDCS) within the past three months.

For TD group:

children were excluded if their scores on the Social Responsiveness Scale (SRS) exceeded the cutoff.

Population composition: TD and ASD. TD: 3-10 years old, with normal vision and corrected vision, hearing, and no social or behavioral problems. ASD: 3-10 years old, diagnosed by a doctor with ASD, normal vision and corrected vision, hearing, etc., but with social and behavioral problems.

Key demographic information: 3-10 years old. TD: 22 males and 6 females. ASD: 24 males and 4 females.

Source and final scale: TD recruited 36 children from Jinhua Primary School and First Kindergarten in Shehong City, Sichuan Province, and ultimately used 28 children. ASD: 52 children from special schools and rehabilitation institutions in some districts and counties of Chengdu were recruited, and 28 were ultimately used.