Anchoring
Anchoring is the tendency to rely too heavily on the first piece of information offered when making a judgement.
Throw out a number, any number, before someone makes an estimate, and you will tug their answer toward it. That pull is anchoring.
Anchoring is the tendency to rely too heavily on the first piece of information encountered, the anchor, when making a judgement, so that subsequent estimates are pulled toward it even when the anchor is irrelevant. The starting point contaminates the conclusion.
How strong the pull is
Anchoring is among the most robust findings in the study of judgement. In experiments, people asked whether a quantity is higher or lower than an obviously arbitrary number, a figure from a spun wheel, the last digits of an identifier, then estimate that quantity closer to the arbitrary number than those given a different one. The anchor need not be plausible or relevant to exert its pull, which is what makes the effect so striking and so easy to exploit.
Where it operates
Anchoring shapes negotiation, pricing, and forecasting constantly. The first offer in a negotiation anchors the range in which the deal settles, which is why making the first reasonable offer is often an advantage. A high recommended retail price anchors what a discount feels like. An initial budget or forecast anchors all the revisions that follow. Wherever a number is estimated against a reference, the reference is doing quiet work.
Defending against it
Because anchoring operates beneath awareness, willing oneself to ignore an anchor barely helps. The better defences are structural: generating one's own estimate before hearing anyone else's, deliberately considering reasons the anchor might be wrong, seeking independent data points, and in negotiation, being ready to re-anchor rather than merely react. The aim is to avoid letting the first number become the gravitational centre of the discussion.
Anchoring is a reminder that judgement is not made in a vacuum but from a starting point, and that whoever sets the starting point holds quiet power. The number mentioned first, however arbitrary, tends to shape every number that comes after it.