A Cross-sectional Study to Evaluate Speech and Language Development in Chinese Children Aged 2-6 Years

Inclusion Criteria: For normally developing children 1. All children must meet all of the following criteria simultaneously: 2. Informed consent of legal guardian or group representative; 3. Age from 2 to 6 years old, male and female; 4. Native speaker of Mandarin; 5. Children in kindergartens and hospitals are professionally assessed as normal development, which is defined as children without intellectual development disorder, developmental speech or language disorder, autism spectrum disorder, and attention deficit hyperactivity disorder. For abnormally developed children 6. Informed consent of legal guardian or group representative; 7. Age from 2 to 6 years old, male and female; 8. Native speaker of Mandarin; 9. Children with intellectual development disorder, autism spectrum disorder and attention deficit hyperactivity disorder are assessed professionally in the hospital; Diagnostic criteria were referred to Diagnostic and Statistical Manual of Mental Disorders (DSM-5) Exclusion Criteria: For normally developing children 1. Poor coordination; 2. Other unsuitable children considered by researchers, such as children whose developmental level is basically normal but whose environmental and socio-economic factors (premature birth, low birth weight, malnutrition, abuse, etc.) have been verified to affect language development. For abnormally developed children 3. Study the poor fit degree; 4. Have visual and hearing impairment; 5. Other unsuitable children considered by researchers, such as children with other organic dysfunction, such as cerebral palsy, congenital genetic diseases, epilepsy, etc.