in: Oxford Research Encyclopedia of Politics
Prospect theory—a psychologically founded account of decision making under risk and uncertainty—revolutionized how economists and, later, political scientists thought about decision making under uncertainty. Conceptually, prospect theory is based on two central notions: reference dependence, which is the notion that the utility of outcomes is defined over changes in outcomes from a reference point instead of over absolute outcome levels; and likelihood dependence, which is the notion that people distort probabilities non-linearly when making a decision. Likelihood dependence gives rise to the possibility and certainty effects—changes in probabilities are given much more weight if they fall toward the probability endpoints than if they fall into intermediate probability ranges. Reference dependence gives rise to the reflection effect, predicting mirrored risk attitudes for gains and for losses; and to loss aversion, predicting that people display a disproportionate dislike for losses.