This article described three heuristics that are employed in making judgements under uncertainty: representativeness, which is usually employed when people are asked to judge the probability that an object or event A belongs to class or process B; availability of instances or scenarios, which is often employed when people are asked to assess the frequency of a class or the plausibility of a particular development; and adjustment from an anchor, which is usually employed in numerical prediction when a relevant value (...) is available. These heuristics are highly economical and usually effective, but they lead to systematic and predictable errors. A better understanding of these heuristics and of the biases to which they lead could improve judgements and decisions in situations of uncertainty. (shrink)

Previous research showed that accumulations of capital following stationary interest rates are underestimated by human judges. Hyperbolic discounting was suggested as a descriptive and explanatory model for this phenomenon. First, we investigated judged accumulated capital after a period of annual growth and decline. The degree of underestimation increased with accumulated growth and the results supported hyperbolic discounting as a descriptive model on the group level. However, the hyperbolic model did not apply to the data for one third of the participants. (...) Second, we investigated how investment decisions were related to capital accumulation before the investments and to judgments of the possible outcomes of the future investments. To our surprise, the participants’ judgments of expected future accumulated capital did not add predictive power to predictions based on whether there was growth or decline before the investment decision. Unfortunately this strategy leads to suboptimal investment decisions. (shrink)