Believe it or Not: Item Prioritization as a Method for Developing and Validating the Trustfulness Redundancy-free Short Test (TRST)

Trustfulness, also known as the propensity to trust, is a dispositional trait reflecting a belief in the general trustworthiness of others across situations. Although researchers have emphasized its importance across multiple sectors, its existing measures have methodological limitations and are often overly content-specific (e.g., trusting a supervisor). Building on prior work that identified and content-validated a preliminary item pool, the present research developed and validated a new, rigorously tested trustfulness scale. Across multiple studies (total N = 3,048), we prioritized modern psychometric practices by first evaluating items directly before conducting structural analyses. Using multi-occasion and multi-rater data, we reduced the scale’s content redundancy, maximized its content breadth and reliability, and assessed its consensual validity. We then evaluated the scale’s structure through exploratory and confirmatory factor analyses and compared its psychometric properties to existing trustfulness measures and to similar but distinct constructs, allowing for tests of convergent and discriminant validity. We present the final product which we call the Trustfulness Redundant-free Short Test (TRST); a 6-item scale consisting of two factors (i.e., Trust Beliefs and Suspicion of Others) that evaluates trustfulness in an efficient and psychometrically sound way.