Development and application of the infant behavior observation scale.

This study aimed to develop a culturally localized Infant Behavior Observation (IBO) scale for Chinese infants aged 0-12 months and to validate its reliability and validity for the early identification of atypical behavioral development. Following standardized scale development procedures, a total of 1280 infants from five provincial regions across China were enrolled. Initial scale items were generated through interviews and refined via exploratory and confirmatory factor analyses. The final version of the IBO scale consists of 36 items covering five core dimensions: social behavior, emotional expression, sense of control, autonomy, and negative emotion regulation, collectively explaining 67.48% of the total variance. Confirmatory factor analysis yielded acceptable model fit, with high internal consistency (Cronbach's α = 0.89) and satisfactory test-retest reliability (r = 0.83). Based on normative percentile thresholds, overall behavioral performance was categorized into four hierarchical developmental levels. The total detection rate of atypical behavioral development was 11.53%, which increased progressively with age.Early behavioral deviations were predominantly characterized by difficulties in negative emotion regulation, whereas atypical social behaviors became increasingly prominent after four months of age. The findings demonstrate that the IBO scale is a psychometrically reliable and valid instrument for evaluating behavioral and socio-emotional development among Chinese infants.