The truth of any proposition has nothing to do with its credibility and vice versa.
—Parker’s law of political statements (Bloch, 1979, p. 84)
Our interest in this article is with the cognitive processes that influence ratings of probable truth. Ideally, a statement should not be accepted as true without factual evidence in support of its claims. However, people often rely on memories for
that evidence. It is sensible to base truth ratings on whether expressed facts corroborate or contradict remembered facts. But memory is imperfect, and it is sensible to trust some remembered facts more than others. We propose that there
are two independent bases on which remembered facts are given credence when people rate truth. One basis is recollection: A statement will be accepted as true if it corroborates remembered facts that are associated with a known, credible
source, and it will be rejected as false if the facts are associated with a discredited source. The other basis is familiarity: A statement will seem true if it expresses facts that feel familiar.
We propose, furthermore, that these two bases differ in the extent to which their influence is controlled rather than automatic. Recollection of source is a controlled use of memory, and its influence on rated truth is intentional. In contrast, increased familiarity is an automatic consequence of exposure, and its influence on rated truth is unintentional.
Our thesis is that source recollection and statement familiarity are independent influences on rated truth, because recollecting and using source information requires intent, whereas the feeling of familiarity that occurs while processing messages occurs unintentionally. An opposing view is that the two influences are not independent: Judgments depend on familiarity only when other bases for judgments are not
available. In the following section, we review the empirical support for the idea that the effect of repetition on rated truth is based on familiarity. Then, we examine evidence that familiarity and recollection are independent bases for judgments of fame and that source recollection is an intentional process. Finally, we return to rated truth and develop an approach by which we can dissociate the intentional influence
of source recollection from the unintentional influence of statement familiarity.