Assessing the Implicit Theory of Willpower for Strenuous Mental Activities Scale: Multigroup, Across-Gender, and Cross-Cultural Measurement Invariance and Convergent and Divergent Validity

Why do some people struggle with self-control (colloquially called willpower) whereas others are able to sustain it during challenging circumstances? Recent research showed that a person's implicit theories of willpower-whether they think self-control capacity is a limited or nonlimited resource-predict sustained self-control on laboratory tasks and on goal-related outcomes in everyday life. The present research tests the Implicit Theory of Willpower for Strenuous Mental Activities Scale (or ITW-M) Scale for measurement invariance across samples and gender within each culture, and two cultural contexts (the U.S. and Switzerland/Germany). Across a series of multigroup confirmatory factor analyses, we found support for the measurement invariance of the ITW-M scale across samples within and across two cultures, as well as across men and women. Further, the analyses showed expected patterns of convergent (with life-satisfaction and trait-self-control) and discriminant validity (with implicit theory of intelligence). These results provide guidelines for future research and clinical practice using the ITW-M scale for the investigation of latent group differences, for example, between gender or cultures. Public Significance Statement A person's implicit theories of willpower-whether they think self-control is a limited or nonlimited resource-predict self-control assessed with laboratory tasks and in everyday life. This study demonstrates that a six-item scale invariantly measures a person's implicit theory of willpower for strenuous mental activities across 10 data sets, two cultural contexts, and men and women.