Host: The Japanese Society for Cognitive Psychology
According to the propositional logic, the probability of conditional if p then q equals to P(¬p∨q). However, many researchers show that people judge that it equals conditional probability (P(q|p)). The data support the the suppositional theory which propose that not-p cases are regarded as void based on De Finetti’s truth table. We adopted the set-choice paradigm whereby participants are given a pair of urns which includes some chips and asked to choose one which gives higher probability of a conditional ‘if p then q’(the probability of conditional). We also set the conditional bet task in the same way. We gathered data from American and Japanese samples via internet, and found that both Japanese and American judged the probability based on the conditional probability, but some judged it based on the principle of conjunction (P(p&q)).
