Anchoring, Confirmatory Search, and the Construction of Values.

Anchoring is a pervasive judgment bias in which decision makers are systematically influenced by random or uninformative starting points. While anchors have been shown to affect a broad range of judgments including answers to knowledge questions, monetary evaluations, and social judgments, little is known about the underlying causes of anchoring. We suggest that anchors affect judgments by increasing the availability and construction of features that the anchor and target hold in common and reducing the availability of features of the target that differ from the anchor. We develop this Confirmatory Search mechanism of anchoring and contrast it with two alternative mechanisms: Averaging and Dynamic Adjustment. To isolate the causes of anchoring, we present six experiments that examine the effects of several experimental manipulations on judgments of value and belief as well as several measures of cognitive processes. Four facts about the anchoring bias were established. First, prompting subjects to consider features of the item that were different from the anchor reduced anchoring, while increasing consideration of similar features had no effect. Second, subjects’ judgments were a linear function of anchor value. Third, items of uncertain value demonstrated a larger anchoring bias than did items of more certain value. Finally , anchoring was unaffected by financial incentives and perceived informativeness of the anchor. We close by showing that a Confirmatory Search approach both provides a mechanism for debiasing anchoring, and unites anchoring with a number of other judgment phenomena.