Anchoring is the tendency for the first number or piece of information encountered to pull later estimates toward it, even when that first figure is arbitrary. The effect was demonstrated by Amos Tversky and Daniel Kahneman in 1974. It is kept deliberately short here: anchoring belongs to the family of mental shortcuts covered in full in the site’s guide to cognitive biases, and this entry exists so readers looking up the term can find its meaning and the fuller guide in one step.
What it looks like
Anchoring appears whenever a starting figure shapes a later judgement. A shop price tag marked “was $200, now $120” makes $120 feel like a bargain, because $200 anchors the comparison. In a negotiation, the first offer on the table tends to pull the final agreement toward it, even when both sides know the opening figure was chosen strategically. A doctor given an early, irrelevant number may unconsciously lean toward it when estimating a quantity.
Why it happens
The usual explanation is that people adjust away from the anchor, but not far enough. Once a number is in mind, it becomes a starting point, and subsequent thinking stays tethered to it. Tversky and Kahneman showed this with a rigged wheel of fortune: participants who spun a high number gave higher estimates for an unrelated quantity than participants who spun a low number, even though the wheel was plainly random. The anchor did not need to be relevant or believable; it only needed to come first. The adjustment is usually too small because the anchor frames what counts as reasonable, and each step away from it feels like a stretch.
An everyday example
A person selling a used bicycle lists it at a high asking price, hoping for a strong offer. A buyer who had planned to offer much less ends up settling near the middle — higher than they intended — because the asking price set the range of the discussion. The final price was not determined by the bicycle’s value alone; it was pulled toward the first number mentioned.