Evidence-based or emotion-based decision-making? The curious case of cancer screening

When difficult trade-offs between potential benefits and harms of medical treatments need to be considered, evidence-based decision making is often recommended.

This means that decision makers need to consider complex numerical evidence in an emotionally-charged context.  Decisions about cancer screening present a useful example of the interplay between decision makers’ capacity to understand complex or counter-intuitive evidence (e.g., screening that is not as life-saving as we would expect or could be harmful) and their emotions or beliefs (e.g., fear of cancer, enthusiasm for cancer screening). To what extent are people’s decisions based on the evidence deemed relevant by experts?

In five experiments (3 with laypersons and 2 with physicians) we investigated the impact of various psychological factors on decisions about screening. We find that decision makers do consider statistical evidence about risks and benefits but to what extent they do so can depend on a number of factors. Our results suggest that the public’s fear of cancer and strong enthusiasm for cancer screening can make them perceive inexistent benefits from screening, while perceived harms barely weigh in decision making. Transparent information formats can help understand the evidence and fostering risk literacy can improve decisions. We need to understand the multifaceted, context-dependent perceptions of risk and benefit to help decision makers evaluate the evidence in a meaningful way.