In 1974, psychologists Amos Tversky and Daniel Kahneman ran a simple experiment that should have made no sense. They spun a rigged roulette wheel - the outcome was entirely random, either 10 or 65 - and then asked participants to guess the percentage of African countries in the United Nations. People who saw the wheel land on 65 guessed significantly higher than people who saw it land on 10. A meaningless random number, generated by a carnival prop, had contaminated an unrelated factual judgment. The participants had no idea it happened.
That experiment described a mechanism your brain uses every day. The mechanism has a name: anchoring.
How the anchor gets planted
An anchor is the first piece of numerical or evaluative information your brain receives in a given context. It does not have to be relevant. It does not have to be accurate. It does not even have to come from a trustworthy source. Once it lands, it becomes the gravitational center around which every subsequent estimate orbits.
Think of it like someone dropping a bag of gravel on one side of a seesaw before you even sit down. You are not starting from level. You are starting from tilted - and you have no way to feel that tilt because it was set before you arrived.
The classic everyday version: you walk into a store. A jacket is marked down from $400 to $240. You have never bought a jacket that costs more than $150 in your life. But $240 feels like a deal, because the anchor - $400 - reframed the reference point before you could set your own. The store did not trick your logic. It occupied the territory your logic was going to use before your logic showed up.
Why adjustments are always too small
Here is the part that makes anchoring particularly hard to escape. Even when you know an anchor is wrong, your corrections tend to be insufficient. Tversky and Kahneman called this the anchor-and-adjust heuristic: you start at the anchor, move in the right direction, and stop when you hit something that feels plausible. The problem is that "feels plausible" is itself influenced by the anchor. You stop too early, still inside its gravitational field.
Key Point: Awareness of anchoring is not enough to neutralize it. Research shows that people who are explicitly warned about anchoring still show the effect - they just adjust slightly further. The anchor is baked into the process of adjustment itself, not only into the starting point.
Precise anchors are more powerful than round ones, which is counterintuitive. If someone says a product costs $1,200, you adjust fairly freely. If they say it costs $1,247, you adjust less - because the specificity signals expertise. Your brain interprets precision as evidence that careful calculation was done, and backs off from challenging it. This is why car dealerships quote to the dollar, not the hundred.
Where this costs you most
In negotiations, whoever names a number first is setting the anchor for everything that follows. Even experienced negotiators end up closer to the first number offered than their rational analysis would suggest. The research on this is consistent across salary negotiations, real estate transactions, legal settlements, and vendor contracts. The person who puts the number on the table first has done something structural to the outcome, not just tactical.
In hiring, interviewers who review a candidate's current salary before forming an assessment make significantly different offers than those who do not. The current salary is, in most cases, irrelevant to the candidate's value in the new role. But it anchors the offer anyway.
In medicine, a doctor who first reads a pessimistic prognosis in a chart approaches a patient with a different lens than one who starts from scratch. Not because the doctor is biased in the usual sense - but because the first information encountered becomes the cognitive floor.
What actually helps
The most effective counter to anchoring is not skepticism alone. It is counter-anchoring: generating your own reference point before the other party's anchor arrives. In a salary negotiation, that means researching market rates and forming your own number before the conversation begins. When you walk into a store, it means deciding what you are willing to pay before you see the tag. When reviewing a report, it means forming a preliminary assessment before reading the summary at the top.
The anchor you set yourself is still an anchor - but it is yours, and it competes with the external one.
Key Point: Pre-commitment to your own reference point is the most practical defense against anchoring. It does not eliminate the bias, but it introduces a competing anchor that pulls you toward your own analysis rather than someone else's.
You will not catch every anchor. Some are embedded in language, in framing, in the order information reaches you. But once you start noticing the number in the room before you got there, you will start asking how it got there - and that question is worth more than any individual adjustment.