People often face choices where outcomes are both delayed and uncertain. Numerous studies of delayed gains and losses show the hyperbolalike discounting process of delayed payoffs. We assumed that when evaluating a delayed lottery people act according to the prospect theory model, where payoffs are discounted according to a hyperbolic function. The problem that we addressed is whether the a parameter of the value function v( ) and the g parameter of the probability weighting function w( ) differ for evaluations of delayed and instant lotteries. We found that when people compare delayed certain payoffs with delayed risky payoffs they are more risk prone than in situations where both certain payoffs and risky payoffs are instant. However, when people compare
present certain payoffs with delayed risky payoffs they are less risk prone than in situations where both certain payoffs and risky payoffs are instant. Additionally, the probability weighting curves were more linear for delayed lotteries than for instant lotteries (people were more sensitive to changes of probability).

This paper presents the results of study on the probability distortion. The distortion is studied at two levels: (i) in the decision maker's perception (expressed as subjective judgements), and (ii) in the decision maker's choices (expressed in decision weights). The study examined how the two types of distortion – concerning perception and weights – depend on the way information on probability is presented. Two formats of probability information were distinguished: descriptive (expressed in numbers) and experience.The results confirmed the hypothesis of lower perceptual distortion of objective probability when the information on payout distribution was presented using the experience-based format than when the information was given as a description. The hypothesis on the lower distortion of probability in decision weights with the experience probability format was not confirmed. An unexpected result was a lower risk seeking with the experience format. This effect seems to be a result of attributing lower weights than with the descriptive format. Furthermore, it appears that the probability distortion in decision weights at least partly results from the distortion in perception.