Validation of a short-form, state version of the Body Appreciation Scale-2 (SBAS-2SF) for use in experience sampling method (ESM) studies

Body appreciation is an important facet of the positive body image construct and can be measured as either trait or state variants. Trait measures of body appreciation evidence good psychometric properties, but less work has focused on state measures, particularly for use in experience sample method (ESM) studies. Here, we assessed the psychometric properties of a short (3-item) form, state version of the Body Appreciation Scale-2 (SBAS-2SF) for use in ESM studies (N = 100, k = 2187). Results showed that the SBAS-2SF demonstrated good composite reliability as a trait measure, as well as high reliability at the daily state level (ICC range .81-.84, generalisability coefficient ρ² = .96). Variance decomposition confirmed that the majority of variability (73.7%) reflected stable between-person differences. Multilevel confirmatory factor analysis supported a unidimensional factor structure at both within- and between-person levels, with uniformly strong factor loadings. Concurrent validity was supported through moderate-to-strong correlations with positive arousal, negative arousal, and self-rated mental health, and through strong correspondence between aggregated daily scores and trait scores. Continuous-time modelling showed that body appreciation reflects a highly self-stabilising dynamic process (drift, a = -1.22), while remaining sensitive to daily affective inputs: positive arousal exerted a strong contemporaneous positive effect, whereas negative arousal and poorer mental health were associated with lower body appreciation. These results suggest that the SBAS-2SF can be used to assess the body appreciation construct in ESM studies, though further validation work would be beneficial.