AbstractWhen several items of information are combined to give an overall judgement, it is usually found that some kinds of item are given greater weight than others. This study examines the relations between three criteria which judges may use in deciding how to apportion these weights. The criteria of evaluative direction and extremity have of ten been studied within impression formation, while demonstrations of the influence of ambiguity have produced unclear findings.Simple models of the combination of these three criteria are shown to be inadequate and a more complex account is suggested. A study is reported in which divergence between the criteria of extremity and ambiguity results in a generally greater bias to negative. This effect is related to other studies of the influence of inconsistency, and range adjustment model of the judgement process is extended to take it into account.