Preliminary Investigations into the Psychological Foundations of Fuzzy Reasoning.

Abstract : In a series of experiments, subjects performed two tasks: pairwise comparison, in which they selected the truer of two sentences; and direct numerical scaling, were they rated truth on a 0-to-100 scale. Results indicated that (1) the high degree of transitivity in each subject's paired-comparison judgments leads us to reject the hypothesis of a two-valued true-false logic in favor of a continuum of values; (2) ability to discriminate, as judged by the consistency between direct ratings and paired-comparison judgments, seems to be uniform along the true-false continuum, again favoring the hypothesis of a continuum of truth values over that of a binary categorical judgment; and (3) the high correlation between an item's aggregate binary preference score for a given subject and that subject's direct rating for the item indicates that at least two different methods of inferring degree of truth are highly consistent. Significance of these results and plans for further efforts to develop scaling methods are discussed.