Human Understandings of Probability

Abstract

In this chapter developments in theories and research on human understandings and judgements of probability are examined. The concept of probability as a degree of belief and the systematic study of human probability judgements have emerged only recently, but have stimulated numerous fruitful debates about the nature of rationality, belief formation, decision-making, and uncertainty itself. The chapter begins with a review of how the connection between probability and degrees of belief was developed and elaborated to form a prescriptive framework, followed by a brief summary of debates concerning rationality and uncertainty. It then surveys models of human probability judgements based on probability weighting functions, ways in which these judgements depend on how relevant information is presented, mental shortcuts (or “heuristics”) underpinning such judgements, the extent to which probability judgements are miscalibrated, fallacies in judgements of probabilities of compound and conditional events, and debates concerning the effective communication of probabilistic information.