We present a family of models of choice between behavioural alternativ
es with stochastic outcomes (risky choice) based on the effects of Web
er's Law in memory. These models generalise and extend a model of risk
sensitive foraging originally proposed by Reboreda & Kacelnik [(1991)
Behav. Ecol. 2, 301-308], which yielded qualitative predictions (risk
-aversion for amount of food and risk-proneness for delay to food). We
now demonstrate how this approach can predict quantitatively the part
ial preferences between two alternative options with any mean and vari
ance in their outcomes, and the certainty equivalent of an option cons
isting of any set of probabilistic outcomes. The approach is also rele
vant to the economics and psychology of risk sensitivity because it pr
edicts risk aversion for any desirable outcome (such as monetary gains
) and risk seeking for any undesirable gain (such as monetary losses).
Our models are process-based rather than purely normative, and are ba
sed on linear expected utility as a function of expected outcomes. The
y do not account for all observed aspects of risky choice, but their d
escriptive performance betters that of existing functional models and
requires fewer parameters. (C) 1998 Academic Press.