Idiosyncratic Weighting of Trait Information in Impression Formation

An analysis is offered of the role of unequal weighting in the averaging model of information integration. A distinction is made between unequal weighting at the normative level (which has been referred to as "differential weighting") and unequal weighting at the level of the individual subject (which we refer to as "idiosyncratic weighting"). Two studies are reported that examine the prevalence of idiosyncratic weighting in the trait-judgment impression formation task. Whereas most past research on the question of unequal weighting in this task involved averaging responses across both subjects and stimulus replications, the present studies were analyzed at the level of an individual subject's repeated responses to separate stimulus replications. Clear evidence of idiosyncratic weighting was obtained from about 50% of the 120 subjects; only 20% of the subjects indicated absolutely no tendency toward unequal weighting. There was no evidence that idiosyncratic weighting was restricted to just a subset of stimuli, since all of the 20 stimulus replications showed idiosyncratic weighting effects. In contrast to previous findings, negative traits did not always receive more weight than positive traits. In more than 20% of the instances of unequal weighting, the more positive trait was accorded a higher weight.