Abstract
BACKGROUND/AIM: Social networks have transformed the traditional dynamics of identity construction in adolescence, allowing users to select content and interact with others who share similar views, thereby reinforcing a sense of belonging to homogeneous groups. Given the growing influence of digital interaction on social identity among youth, psychometrically sound instruments are needed to measure this process. This study aimed to evaluate the psychometric properties of both the 9-item (IBRS-9) and 6-item (IBRS-6) versions of the Identity Bubble Reinforcement Scale in a large sample of Chilean adolescent students. METHODS: A cross-sectional design was used with 4096 participants (50.8% male, 47.8% female, 1.4% other; M = 15.82, SD = 1.30) from 41 secondary schools across Chile. Confirmatory factor analyses (CFAs) tested factorial validity, and internal consistency and external criterion validity were examined. Measurement invariance was assessed across sex, social media use, internet use, and age. Analyses were conducted using the WLSMV (Weighted Least Squares Mean and Variance Adjusted), and model evaluation was based on conventional goodness-of-fit indices. RESULTS: CFAs supported the factorial validity of both IBRS versions, showing reliability and external criterion validity. Model fit indices indicated good fit for both scales. Invariance analyses confirmed factorial stability up to the strict level across all subgroups, indicating consistent psychometric performance. CONCLUSIONS: The IBRS-9 and IBRS-6 are valid and reliable instruments for assessing identity bubble reinforcement among Chilean adolescents, providing evidence of factorial stability and applicability for research and educational and psychosocial interventions. Their validated structure provides a consistent basis for examining social identity processes related to digital interaction.