Table 1 Participant Information

Category		Participant A	Participant B	Participant C
Age / Sex		4 years 6 months(Male)	4 years 9 months(Male)	6 years 10 months(Male)
Diagnosis / Clinical Impression		Autism Spectrum Disorder	Developmental delay	Autism Spectrum Disorder
Diagnostic assessments	CARS-21	32	-	37
	ADI-R2	Social interaction 20Qualitative abnormalities in communication and play 8Repetitive and stereotyped behaviors 4Evidence of onset before 36 months 4	-	Social interaction 20Qualitative abnormalities in communication and play 16Repetitive and stereotyped behaviors 8Evidence of onset before 36 months 4
	ADOS-23	23	-	24
Language assessments	PRES4	• Receptive language: 19(4;6)• Expressive language: 21(4;6)	-	-
	SELSI5	-	• Receptive language: 17(4;2)• Expressive language: 15(4;2)	-
Developmental assessment	K-Bayley-Ⅲ6	-	• Receptive language: 15(4;2)• Expressive language: 17(4;2)	-
Common characteristic		· Generalized imitation

CARS-2: Childhood Autism Rating Scale, Second Edition
ADI-R: Autism Diagnostic Interview–Revised
ADOS-2: Autism Diagnostic Observation Schedule, Second Edition
PRES: Preschool Receptive-Expressive Language Scale
SELSI: Sequenced Language Scale for Infants
K-Bayley-III: Korean Bayley Scales of Infant and Toddler Development, Third Edition