The denominator neglect in decision-making

Abstract

People often pay too much attention to numerators and inadequate attention to denominators, this phenomenon is called denominator neglect. The aim of the study was mapping of frequency of denominator neglect, comparison of results with results of other studies and examination of possible moderators of denominator neglect. In two studies a total of 533 participants complete the Jellybean task, Vienna Matrix Test, Master Rationality Motive Scale, Cognitive Reflection Test, and Rational-Experiential Inventory. Results show that 1) denominator neglect was strongest in case of 8% probability (regardless whether alternative probabilities were equal or unequal), 2) motivated participants made significantly less suboptimal choices than unmotivated participants, and 3) there was no effect of cognitive ability, motive for rational integration and experiential thinking disposition, but low cognitive reflection and rational thinking style predicted denominator neglect.