In 1974, psychologists Amos Tversky and Daniel Kahneman ran an experiment that would reshape our understanding of human judgment. They spun a wheel of fortune rigged to land on either 10 or 65, then asked participants to estimate the percentage of African nations in the United Nations. The wheel had nothing to do with African geopolitics. But participants who saw the wheel land on 65 gave estimates that were, on average, far higher than those who saw it land on 10.
This is anchoring — the tendency for an initial piece of information, even if arbitrary or irrelevant, to disproportionately influence subsequent judgments. It is one of the most robust findings in all of cognitive psychology, and it affects far more than trivia guesses.
How Anchoring Works
When we encounter a decision that requires estimation — How much should this house cost? How long will this project take? What salary should I ask for? — our minds don't start from a blank slate. We start from whatever number happens to be available, and we adjust from there. The problem is that the adjustment is almost always insufficient. We stay too close to the anchor.
Tversky and Kahneman called this anchoring and adjustment, and in their landmark 1974 paper "Judgment Under Uncertainty: Heuristics and Biases," published in Science, they identified it as one of the core heuristics that shape human reasoning.
The effect is startlingly strong. In one study, German judges — experienced professionals trained to weigh evidence impartially — were asked to read about a shoplifting case and then roll a pair of dice (secretly loaded to land on either 3 or 9) before deciding a sentence. Judges who rolled a 9 gave significantly longer sentences than those who rolled a 3. The dice had no legal relevance whatsoever. The judges knew it. It didn't matter.
This study, conducted by Birte Englich, Thomas Mussweiler, and Fritz Strack and published in the Journal of Applied Social Psychology in 2006, is one of the most unsettling demonstrations of anchoring: even experts in high-stakes domains are not immune.
Why the Brain Does This
Anchoring likely persists because it is, in most situations, a useful shortcut. We live in an environment overflowing with estimation tasks. How far is the grocery store? How long will dinner take to cook? How much should a decent winter coat cost? Starting from a reference point and adjusting is faster and usually good enough.
The problem arises when the reference point is arbitrary, manipulative, or irrelevant — and our adjustment doesn't go far enough. Psychologist Timothy Wilson and colleagues at the University of Virginia demonstrated in a 1996 study that even when people are explicitly told the anchor is random, the effect persists. Knowing about anchoring doesn't make you immune to it. The bias operates below the level of conscious correction.
More recent research suggests anchoring may involve two mechanisms. The first is the adjustment model Tversky and Kahneman proposed — we start at the anchor and move away, but stop too soon. The second is selective accessibility, proposed by Mussweiler and Strack: the anchor causes us to selectively retrieve information from memory that is consistent with it. If someone says "Is the population of Chicago more or less than 10 million?", your brain starts searching for reasons why it could be 10 million — even as you logically know it isn't.
Anchoring in Daily Life
Once you learn to see anchoring, you notice it everywhere:
Negotiations. The first number placed on the table — whether it's a salary offer, a home listing price, or a freelance rate — becomes the anchor around which the entire negotiation orbits. Research by Adam Galinsky and Thomas Mussweiler, published in the Journal of Personality and Social Psychology in 2001, found that the party who makes the first offer typically achieves a more favorable outcome, because they set the anchor.
Retail pricing. The original price on a "50% off" tag isn't just information — it's an anchor. You evaluate the sale price relative to the original, even if the original was inflated. This is why retailers display the "was" price prominently. The higher the anchor, the better the deal feels.
Medical judgment. Studies have shown that initial diagnostic impressions can anchor physicians on a particular diagnosis, making them slower to revise their assessment even when new evidence points elsewhere. A 2008 review by Pat Croskerry in Academic Medicine identified anchoring as one of the most common cognitive errors in clinical reasoning.
Sentencing and law. Beyond the dice study, research has shown that prosecutor sentencing recommendations serve as powerful anchors for judges, even when the recommendations are extreme.
Can You Overcome It?
The honest answer is: partially. Complete de-biasing is unlikely — anchoring operates too automatically. But there are strategies that help:
Consider the opposite. When you notice an anchor influencing your judgment, deliberately generate reasons why the true answer might be very different. This technique, supported by research from Mussweiler, Strack, and Pfeiffer (2000), helps counteract the selective memory retrieval that anchoring triggers.
Generate your own anchor first. Before entering a negotiation or making a decision, form your own independent estimate. Having a pre-committed number makes you less susceptible to someone else's anchor.
Use ranges instead of points. Rather than fixating on a single number, think in terms of a plausible range. This broadens your consideration set and weakens the pull of any single anchor.
Slow down. Anchoring is strongest when we're making quick, intuitive judgments. Deliberate, systematic thinking — what Kahneman calls System 2 — partially mitigates the effect, though it doesn't eliminate it entirely.
The Uncomfortable Implication
Anchoring reveals something fundamental about how we think: we don't evaluate information in a vacuum. Every judgment we make is relative — shaped by context, comparison, and whatever number happened to arrive first. This isn't a flaw we can simply decide to fix. It's a feature of the cognitive architecture we're working with.
The best we can do is know it's happening, plan for it, and build habits that create better starting points for the decisions that matter most.
