THE CONJUNCTION FALLACY - DIFFERENTIAL INCIDENCE AS A FUNCTION OF DESCRIPTIVE FRAMES AND EDUCATIONAL CONTEXT

The frequency of the conjunction fallacy, in which individuals report that the conjunction of two events is more rather than less likely tha n one of the events alone, was assessed in college students when quest ions were asked with and without a ''framing description,'' when nothi ng was known about the person being judged, in questions presented in a more qualitative format, and between groups studying different subje cts. The frequency of the fallacy varied sharply across student groups and groups differed in their susceptibility to contextual effects. Im portantly, the conjunction fallacy occurred for about one-quarter of s ubjects even when the framing description was eliminated and the quest ion worded to facilitate a logical approach. Experiment 2 found that s ubjects' descriptions of their problem-solving strategies appeared lar gely unrelated to their performance. In Experiment 3, logic students p erformed the task near the end of their course; a substantial number, 43%, committed the fallacy. In Experiment 4, 41% of students committed the fallacy even without the framing description. (C) 1996 Academic P ress, Inc.