AGING AND CREDIBILITY JUDGMENT

The purpose of this study was to investigate the effect of aging on cr edibility judgments and source memory for statements expressing new '' factual'' knowledge. In Experiment 1, we examined the influence of fam iliarity in young and older adults' credibility judgments by comparing their truth ratings for repeated and nonrepeated statements of unknow n credibility. In Experiment 2, we provided information on the actual truth or falsity of some of the repeated statements to determine wheth er this objective evidence would have less influence in older adults' later credibility judgments than in younger adults' judgments. In both experiments, we examined age-related differences in source memory for the statements. The major findings were as follows: (a) the influence of knowledge familiarity as a subjective basis for credibility judgme nt did not decline with age; (b) compared to young adults, older adult s were just as likely to use objective evidence of statement credibili ty in their judgments when this evidence confirmed the truth of their knowledge, but were somewhat less likely to do so when this evidence d isconfirmed the truth of their knowledge; and (c) older adults' memory for the source of their knowledge was consistently less accurate than that of young adults. These findings suggest that older adults will n ot be at a disadvantage relative to young adults when their credibilit y judgments can be based on the subjective evidence of knowledge famil iarity, but they will sometimes be at a disadvantage when a more objec tive basis for judgment is required. In particular, age-related declin es in the ability to process evidence that disconfirms the credibility of knowledge may lead to a magnification of the natural tendency to b elieve rather than disbelieve (cf. Gilbert, 1991).