抄録
Since many things may be subjectively judged as partially true or partially false rather than absolutely true or false, it is important to investigate how the human integrates fuzzy logical informations. Three rules of conjunction in fuzzy logic, that is, minimum rule, multiplying rule, and averaging rule were compared. Thirty subjects judged the truthfulness of single propositions and conjunctions of two to five propositions. The results showed that the subjectively judged truthfulness of the conjunction was closest to the minimum value of the truthfulness of the component propositions, that is, the minimum rule provided the best fit to the data for every conjunctions. However, it is suggested that the human is sensitive to the information from all of the propositions in the conjunction as predicted from the multiplying rule, because the subjectively judged truthfulness of the conjunction tended to become smaller than the minimum value.
