LINDA VERSUS WORLD-CUP - CONJUNCTIVE PROBABILITIES IN 3-EVENT FICTIONAL AND REAL-LIFE PREDICTIONS

Conjunction errors in probability judgments have been explained in ter ms of representativeness, non-normative combination procedures, and li nguistic, conversational, or conceptual misunderstandings. In two stud ies, a three-event variant of the classical Linda scenario (Tversky an d Kahneman, 1983) was contrasted with estimates of Norway's chances in three coming World Cup soccer matches. Conjunction errors occurred ev en in the latter, real-life prediction task, but much less frequently than in the fictional Linda case. Magnitude of the conjunction effect was found to be dependent upon type of probability (fictional versus d ispositional), unequal versus equal probabilities of constituent event s, predictions of positive versus negative outcomes, and, for real-lif e predictions only, number of constituent events. Fictional probabilit y ratings were close to but lower than representativeness ratings, giv ing evidence for a representativeness and adjustment-for-uncertainty s trategy, whereas probabilities of real-life events were given a causal model interpretation.