2010 Volume 22 Issue 4 Pages 464-470
This study analyzed modes of reasoning on the Bayesian problem which could be solved with a basic first-order quantification of probability. Junior high school students (n=33) and university students (n=48) participated in this study. The results were as follows: The Bayesian problem which could be solved with a basic first-order quantification of probability (type 1 problem) was more difficult than the basic first-order quantification of probability problem (type 2 problem) but easier than the original Bayesian problem (type 3 problem). It demonstrates that the level of difficulty of problems depends on how they are framed. In addition, although the same modes of reasoning appeared, the cognitive processes behind them were different between junior high school students and university students. It suggests the importance of a developmental perspective in researches on judgment under ambiguity. Ambiguity can be interpreted as a perturbation factor that has effects on the function of the cognitive system (Piaget, 1970/2007) in the Ellsberg paradox (Ellsberg, 1961), while the framing can be interpreted as such a factor in the problems used in this study. In other words, this study demonstrates that judgments deviate from the normative theory of probability under unambiguity as judgments deviate from the independence axiom of expected utility theory under ambiguity.
