Combining information from sources that vary in credibility

Models describing the role of source credibility in information integration were tested in two experiments. In the first experiment, subjects estimated the value of used cars based on two cues: blue book value and an estimate provided by one of three friends who examined the car. The three sources were described as differing in mechanical expertise. In the second experiment, subjects rated the likeableness of persons described by either one or two adjectives, each adjective contributed by a different source. The sources differed with respect to the length of their acquaintance with the person to be rated. In both experiments, credibility of the source magnified the impact of the information he provided. Further, this multiplicative effect of a source was inversely related to the credibility of the other source, in violation of additive or constant-weight averaging models, but consistent with a relative-weight averaging model.