Scale Effects in Moral Relevance Assessment

Research on moral judgment often employs bipolar rating scales to assess whether the difference between two contrasted options is judged to be morally relevant. We give an account of how different numbers of response options provided on such scales (odd vs. even) change the meaning of the test question by communicating different implicit presuppositions. We demonstrate experimentally that these changes can qualitatively affect the moral relevance judgments that subjects express in response to a given judgment problem. Several alternative explanations in terms of trivial measurement distortion are tested and refuted, and we present suggestive evidence as to what kind of factors might be prone to scale effects. The findings underscore that expressed moral judgments are constructed ad hoc and do not necessarily reflect the content of underlying stable moral commitments. We discuss implications for theories and methodology in moral psychology and in judgment and decision-making research more generally.