A Single-Item Measure of (Non)Essentialist Beliefs About Aging: Reliability, Validity, and Application

Change is an inherent part of aging, which can be understood through the lens of whether such changes are primarily determined by biological factors, such as genetic inheritance, or whether they are shaped by human experiences and adaptability. This paper introduces a single-item scale for assessing these (non)-essentialist beliefs about aging ([N]EBA-SIS). This measure assesses individuals' perceptions of the aging process on along a continuum line, ranging from "genetically predetermined and immutable" to "malleable and changeable." Two studies (N1 = 164, 54 - 75 years and N2 = 98, 67 - 96 years) provide converging evidence of the validity (convergent, divergent, and test-retest) of the (N)EBA-SIS across various contexts (online and paper pencil studies) and populations (healthy adults and geriatric patients). Results demonstrate that the (N)EBA-SIS has strong reliability and validity, including robust test-retest reliability over a four-month period. Given that (non)essentialist beliefs about aging can be represented on a continuum, they can be effectively captured with a single item. Thus, the current research suggests that the (N)EBA-SIS is a valid, reliable and ready-to-use instrument for measuring the (non)essentialist beliefs about aging.