IMPLICIT DIAGNOSTICITY IN AN INFORMATION-BUYING TASK - HOW DO WE USE THE INFORMATION THAT WE BRING WITH US TO A PROBLEM

Past research suggests that people may make use of diagnosticity infor mation when explicit data regarding P(D\H) and P(D\similar to H) are g iven to them. However, people fall victim to pseudodiagnosticity biase s and ignore P(D\similar to H) when such data must be actively sought. This series of four experiments utilized judgment problems in which s ubjects have knowledge of P(D\similar to H) but must recognize the rel evance of that knowledge for the judgment at hand. It was hypothesized that subjects who genuinely understood the role of P(D\similar to H) in hypothesis testing would respond to this manipulation of implicit d iagnosticity by exhibiting greater confidence and lesser information b uying when given evidence of relatively high diagnosticity. In the fir st three studies, subjects attempted to judge the guilt or innocence o f suspects in several fictional crimes. In the fourth experiment, subj ects attempted to judge the club membership status of students at thei r own university, Greater amounts of information were bought when the only available information was of low diagnosticity. Subjects also exp ressed greater confidence in judgments made using highly diagnostic in formation. However, within the legal scenario, sensitivity to diagnost icity was dependent upon the implication of the cues received. Results are discussed with respect to Bayesian probability, expected value th eory, and a confidence criterion model of information purchasing.