Measuring Morality: An Examination of the Moral Foundation Questionnaire's Factor Structure.

Moral foundations theory proposes five domains of morality-harm, fairness, loyalty, purity, and authority. Endorsement of these moral domains is assessed by the Moral Foundations Questionnaire (MFQ), a 30-item scale that has undergone intense measurement scrutiny. Across five samples (N = 464,229), we show greatly improved model fit using a Bifactor model that accounts for two kinds of items in the MFQ: judgment and relevance. We add to this space by demonstrating how using this improved measurement structure changes the strength of correlations of the moral foundations with numerous attitudes, cognitive styles, and moral decision-making. Future research should continue to identify what, if anything, the relevance and judgment factors might substantively capture over and above the substantive domains of moral foundations. In the meantime, we recommend that researchers use the Bifactor model for its improved model structure, rather than dropping the relevant items as some have proposed.