Anchoring the anchor: judgments of both items assimilate in item-based anchoring

Anchoring is a prominent judgment bias which causes people's estimates of uncertain quantities to assimilate towards recently encountered values. Here, we ask whether items can cause anchoring - will the question "Does a handheld flashlight torch cost more or less than a laptop?" induce anchoring in the same way as "Does a handheld flashlight torch cost more or less than £500"? We present evidence from ten studies suggesting that it can, and that perceptions of the value of the anchor item (e.g., the laptop) are also anchored. In other words, estimates for both items being compared assimilate towards each other. We also find that low value items are anchored more strongly than high value items. Overall, there is evidence for a small anchoring-by-items effect (Hedge's g = 0.25), which we suggest previous studies may have been underpowered to detect. Among existing theories of anchoring, Selective Accessibility would appear to provide the best account of the data.