The paper deals with multiple decision problems, which are similar to the task of guessing the color outcomes of five independent spinnings of a roulette wheel, 60% of whose slots are red and 40% white. Each correct guess yields a prize of $1. The guess of 5 Reds clearly first order stochastic dominates any other strategy. In contrast, subjects diversify their choices when facing a multiple decision problem in which the choice is between lotteries with clear objective probabilities. The diversification (...) is stronger when the subjects face uncertainty without objective probabilities and weaker when the choice problem involves real life actions. c 2002 Elsevier Science B.V. All rights reserved. (shrink)