Validation of the Portuguese PACS-3 Frequency Scale: Individual differences in appearance comparison across proximal, distal, and muscularity contexts

Background Social comparison processes focused on physical appearance are key mechanisms in body dissatisfaction and related psychopathology. However, no validated instrument exists to assess appearance comparison frequency in Portuguese adults, limiting research and clinical practice; Objectives This study examined the factor structure and psychometric properties of the Portuguese version of the Physical Appearance Comparison Scale-3 Frequency (PACS-3) in Portuguese adults; Methods A total of 406 Portuguese adults (52% female) aged 18–75 years completed the PACS-3 and measures of appearance-related distress (DAS-14), body appreciation (BAS-2), and body image salience and valence (CARSAL/CARVAL). The sample was randomly split for exploratory factor analysis (n = 193) and confirmatory factor analysis (n = 213). Multi-group confirmatory factor analysis tested measurement invariance across gender; Results Exploratory and confirmatory factor analyses supported an 8-item, three-factor structure (proximal, distal, muscularity-related comparisons). The model showed excellent fit (CFI = .99; RMSEA = .014; SRMR = .031). Internal consistency was excellent (α = .95). Convergent validity showed positive associations with appearance-related distress (r = .653) and body image salience (r = .458), while discriminant validity showed negative associations with body appreciation (r = -.556); Conclusions The Portuguese PACS-3 demonstrated good psychometric properties in a community-based online sample of Portuguese adults. While it shows promise for research and clinical screening, its generalizability to clinical populations and other Portuguese-speaking contexts requires further validation.