Affect Heuristic and Format Effect in Risk Perception

Abstract

The affect heuristic can evoke a format effect so that different ways of expressing the level of likelihood of an event happening can cause different perceptions of the level of risk. We conducted 3 studies to test the hypothesis that a format effect is not always present at every level of probability, and even when a format effect occurs, it depends on risk level and emotion. In Study 1, the risk of a flood threatening participants' homes (familiar risk) regardless of change in emotion, occurred only at a 5% probability level. In Study 2, when facing an unfamiliar risk (being infected by Chikungunya fever), regardless of change in emotion, a format effect occurred at the level of 5% probability only when emotion was positive. In Study 3, a format effect occurred at a 5% probability level when prior emotion expectation was positive and risk consequences were emphasized. We can conclude that the format effect depends on changes in risk level and emotions.