When Effortful Thinking Influences Judgmental Anchoring: Differential Effects of Forewarning and Incentives on Self-generated and Externally Provided Anchors

Two experiments examined the impact of financial incentives and forewarnings on judgmental anchoring effects, or the tendency for judgments of uncertain qualities to be biased in the direction of salient anchor values. Previous research has found no effect of either manipulation on the magnitude of anchoring effects. We argue, however, that anchoring effects are produced by multiple mechanisms—one involving an effortful process of adjustment from ‘‘self-generated’’ anchors, and another involving the biased recruitment of anchor-consistent information from ‘‘externally provided’’ anchors— and that only the former should be influenced by incentives and forewarning. Two studies confirmed these predictions, showing that responses to ‘‘self-generated’’ anchors are influenced by both incentives and forewarnings whereas responses to ‘‘externally provided’’ anchors are not. Discussion focuses on the implications of these effects for debiasing efforts. Copyright # 2005 John Wiley & Sons, Ltd. key words anchoring; bias; incentives; effortful thought