Biases in Improvement Decisions: People Focus on the Relative Reduction in Bad Outcomes

People often decide whether to invest scarce resources—such as time, money, or energy—to improve their chances of a positive outcome. For example, a doctor might decide whether to utilize scarce medicine to improve a patient’s chances of recovery, or a student might decide whether to study a few additional hours to increase their chances of passing an exam. We conducted 11 studies ( N = 5,342 adults) and found evidence that people behave as if they focus on the relative reduction in bad outcomes caused by such improvements. As a consequence, the same improvements (e.g., 10-percentage-point improvements) are valued very differently depending on whether one’s initial chances of success are high or low. This focus on the relative reduction of bad outcomes drives risk preferences that violate normative standards (Studies 1a–1g and 2a), is amplified when decisions become more consequential (Study 2b), and leads even experienced professionals to make suboptimal decisions (Study 3).