Measuring state functionality appreciation: A psychometric evaluation of an adapted version of the functionality appreciation scale (S-FAS)

Within the body functionality and body image research, there is an absence of psychometrically validated measures for capturing functionality appreciation as a state-like construct. To address this, we conducted an extensive psychometric analysis of a state version of the Functionality Appreciation Scale (FAS; Alleva et al., 2017), initially offered by Alleva et al. (2024b), across two online studies. Exploratory factor analyses among a UK-based community sample of 583 adults (18-85 years; age M = 34.66) led to the extraction of a 7-item, unidimensional model of S-FAS scores, which presented adequate composite reliability and good patterns of construct validity (i.e., convergent, concurrent, incremental). Using confirmatory factor analyses, we cross-validated the optimal model among a second community sample of 295 adults (18-78 years; age M = 38.65) from the United Kingdom. Results showed that the unidimensional model of S-FAS scores had adequate fit, demonstrated discriminant validity, and provided additional evidence of measurement invariance (up to latent mean level) across gender identity (women, men) and time (i.e., at pre-test and post-test). Our findings further showed that the S-FAS is sensitive to experimental manipulation and thus accurately captures changes in state functionality appreciation. Overall, the S-FAS is a psychometrically valid measure for assessing functionality appreciation as a state-like construct in future research and practice.