Effects of Reporting Beliefs in Syllogistically Related Propositions on the Recognition of Unmentioned Propositions

Subjects completed a belief questionnaire that contained propositions of the form "X implies Y." In some cases, the questionnaire items included both premises and the conclusion of a syllogism of the form "A implies B, B implies C, A implies C" (e.g., "Taking vitamin C will increase resistance to infection," "Increasing resistance to infection will prevent colds," and "Taking vitamin C will prevent colds"). In other cases, one or more of these propositions was omitted. Later on, subjects were asked whether each of several propositions had or had not appeared in the form they completed earlier. Correct recognition of a statement that had actually been contained in the questionnaire was not appreciably affected by other statements in which beliefs were reported. However, false recognition of a statement that had not been contained in the questionnaire was substantially increased by reporting beliefs in other statements that were syllpgistically related to it. These effects occurred over and above the effect of simply having been previously exposed to the concepts specified in the propositions being recognized and occurred regardless of whether the proposition to be recognized was the conclusion or a premise of the syllogism set. Results we,re interpreted both in terms of the role of syllogistic reasoning in belief processes and in terms of a conceptualization based on Abelson and Reich's implicational molecule theory.