2005 年 32 巻 2 号 p. 109-119
This study investigated how individuals interpret the overall meaning of two Japanese statements of verbal probability reporting the likelihood of an event's occurrence, and what kinds of factors affect these interpretations. Previous research has focused mainly on the interpretation of verbal probability expressed in a single statement regarding the occurrence of a single event. Although we are often given multiple statements about the likelihood of a single event's occurrence in our daily conversation, few studies have examined such instances of multiple information presentation. In this experiment, participants answered a series of choice questions presented in booklets. From their answers, certainty equivalents of single verbal probability statements and of two statements were calculated. The data show that interpretations of the overall meaning of the two probability statements were affected by the following factors: factors of the type of outcome (gain or loss), presentation order, and degree of inconsistency between the statements. Interpretations of the overall meanings were less than the simple average of two statements, and were not interpreted as larger (or smaller) than the likelihood of each statement.