Anchoring Bias: Meaning, Examples and the Research Behind It

By the IQ Revealed Team · Updated November 4, 2026

Anchoring bias is the tendency for a number you have just seen to pull your next estimate towards it, even when that number is irrelevant. A list price, a first offer, a figure in a question or a random number can all act as the anchor. People adjust away from it, but usually not far enough. Also called the anchoring effect, it is one of the most reliably reproduced cognitive biases.

Anchoring bias at a glance

What happens: an initial value, relevant or not, biases a later numerical judgement towards itself.
Classic study: Amos Tversky and Daniel Kahneman, 1974, with a wheel of fortune and a question about the United Nations.
Other names: anchoring effect, anchoring and adjustment, the anchoring heuristic.
How robust: among the very large effects in a 2014 replication across 36 samples and 6,344 people.
Who shows it: students, consumers, negotiators and experienced judges alike; higher ability weakens it only partly.

The wheel of fortune experiment

In their 1974 article in Science, Tversky and Kahneman described anchoring as one of three shortcuts people use to judge under uncertainty. In one demonstration, a number between 0 and 100 was produced by spinning a wheel of fortune in front of the participants. They first said whether the quantity in question was higher or lower than that number, then gave their own estimate.

Asked what percentage of African countries were members of the United Nations, the group whose wheel showed 10 gave a median estimate of 25; the group whose wheel showed 65 gave 45. The number was obviously random, yet it moved the answers by 20 points. Paying people for accuracy did not reduce the effect.

A second study showed that people can anchor on their own partial work. High school students had 5 seconds to estimate a product written on a blackboard. For 1×2×3×4×5× 6×7×8 the median estimate was 512; for the same numbers in descending order, 8×7×6×5×4×3×2×1, it was 2,250. The correct answer is 40,320. Both groups started from the first few steps and adjusted too little, and the group that started with bigger numbers ended higher.

Why anchoring happens

Insufficient adjustment. In Tversky and Kahneman's account, people start from the anchor and adjust, but stop too soon. Nicholas Epley and Thomas Gilovich showed in 2006 that when people generate the anchor themselves, they adjust until they reach the first value that seems plausible, unless they are able and willing to search further for a better answer.
Selective accessibility. Fritz Strack and Thomas Mussweiler, at the University of Würzburg, argued in 1997 that anchoring is a kind of priming. Asking whether the answer is above or below the anchor makes information consistent with the anchor easier to bring to mind, and that information then shapes the estimate.
Basic anchoring. Timothy Wilson and colleagues found in 1996 that an uninformative number can influence a judgement even when people are not asked to compare it with anything, provided they pay enough attention to it. People who knew more about the topic were less affected.

The explanations are not rivals so much as different routes to the same result, and which one dominates depends on where the anchor comes from.

Anchoring in courts, shops and negotiations

Sentencing. Birte Englich, Thomas Mussweiler and Fritz Strack found in 2006 that experienced legal professionals moved their sentences towards a prosecutor's demand even when it came from an irrelevant source, when they were told it had been set at random, and when they had thrown the dice to set it themselves. Expertise and experience did not reduce the effect.
Prices. In six experiments, Dan Ariely, George Loewenstein and Drazen Prelec showed in 2003 that what people would pay for familiar products and experiences was strongly influenced by arbitrary anchors, sometimes derived from their social security number, and that experience with a good did not make the effect go away.
Negotiation. In three experiments, Adam Galinsky and Thomas Mussweiler found in 2001 that whichever side made the first offer, buyer or seller, got the better outcome, and first offers strongly predicted the final price. The advantage disappeared when the other side focused on information that contradicted the offer, such as their own target price.

Is the effect real? What replications show

Anchoring has come through the replication crisis better than many famous findings. In the first Many Labs project, published in 2014, teams in the United States and other countries, including Brazil, the Czech Republic, Italy, the Netherlands, Poland and Turkey, re-ran 13 classic effects with 36 samples and 6,344 participants. Ten effects replicated consistently, and the four anchoring questions, such as estimating the height of Mount Everest after seeing a number that was too high or too low, were among the very large effects. The size varied between samples, which the authors linked partly to how much people already knew about each question.

Some of the more surprising claims deserve more caution. In 2014 Zacharias Maniadis, Fabio Tufano and John List presented new evidence on how strong certain anchoring results in economic valuations really are, and argued that a few independent replications are needed before trusting an initial finding. The honest summary: anchoring on numbers people consider before an estimate is very robust; the size of more exotic versions is less settled.

Does a high IQ protect you from anchoring?

Only partly. Keith Stanovich and Richard West reported in 2008 that, across seven studies, a large number of classic thinking biases, including anchoring effects, were uncorrelated with cognitive ability. Their results suggest that being good at the kind of reasoning an IQ test measures does not automatically switch off this shortcut.

Other data point to a modest benefit. In 2010 Oscar Bergman and colleagues at the Stockholm School of Economics reproduced the social-security-number result and found that the anchoring effect decreased with higher cognitive ability but did not vanish. Read together, the studies suggest that ability helps a little, knowledge of the topic helps more, and nobody is immune. Our pages on critical thinking and metacognition look at the thinking habits that help with errors like this one.

Related biases

The availability heuristic is the second of Tversky and Kahneman's three shortcuts: judging how common something is by how easily examples come to mind. The difference: availability works from the examples your memory supplies, anchoring from a starting value put in front of you.
Confirmation bias resembles selective accessibility: once a possibility is on the table, evidence that fits it gets more attention.
The sunk cost fallacy lets what you have already spent steer the next decision; anchoring lets the first number you saw steer the next estimate.

How to reduce anchoring bias

Make your own estimate first. Before you see a list price, an opening offer or someone else's forecast, write down your own figure and your reasons.
Consider the opposite. Thomas Mussweiler, Fritz Strack and Tim Pfeiffer found in 2000 that listing arguments against a given anchor reduced its effect, including among experts in a real-world setting.
Focus on your own information in negotiations. Thinking about your own target or the other side's alternatives cancelled the first-offer advantage in Galinsky and Mussweiler's studies.
Do not rely on warnings alone. In the 1996 study by Wilson and colleagues, anchoring was difficult to avoid even when people were forewarned. People who knew more about the topic were less affected.

Trust and scope notes

This page summarises published research for general information, with figures taken from the studies listed below. It is not legal, financial or negotiating advice. The IQ Revealed test is an online reasoning test of 40 original items for adults aged 18 and over; it does not measure anchoring bias or any other thinking bias. Our guide to how accurate IQ tests are explains what an online test can and cannot tell you.

IQ Revealed is not affiliated with, endorsed by or connected to the researchers, universities, journals, publishers or replication projects named on this page. Names are used only to identify the research being described.

Frequently asked questions

What is anchoring bias?＋

Anchoring bias, also called the anchoring effect, is the tendency for a number you have just seen or thought about to pull your next estimate towards it, even when the number is irrelevant. People start from the anchor and adjust, but usually not far enough, so estimates end up biased towards the starting value.

What is an example of anchoring bias?＋

In Amos Tversky and Daniel Kahneman's classic 1974 study, a wheel of fortune was spun in front of participants to produce a number between 0 and 100. They were then asked what percentage of African countries were in the United Nations. The median estimate was 25 for the group whose number was 10, and 45 for the group whose number was 65. Everyday examples include a high list price that makes a discount look generous, or a first offer that shapes where a negotiation ends.

Who discovered the anchoring effect?＋

The term and the best-known demonstrations come from the psychologists Amos Tversky and Daniel Kahneman, who described "adjustment from an anchor" as one of three judgement heuristics in a 1974 article in Science, alongside representativeness and availability.

Why does anchoring happen?＋

There are two main explanations, and both seem to be true in different situations. One is insufficient adjustment: people move away from the anchor until they reach a value that seems plausible and then stop. The other, the selective accessibility model of Fritz Strack and Thomas Mussweiler, is that considering the anchor brings to mind information that fits it, and that information then shapes the estimate.

Does anchoring affect experts?＋

Yes. In studies by Birte Englich, Thomas Mussweiler and Fritz Strack published in 2006, experienced legal professionals' sentencing decisions moved towards a sentencing demand even when they knew it had been chosen at random, and even when they had rolled the dice themselves. Expertise and experience did not reduce the effect.

Do smarter people show less anchoring bias?＋

Somewhat, but they are not immune. Keith Stanovich and Richard West reported in 2008 that anchoring was among many thinking biases that were uncorrelated with cognitive ability in their studies. A 2010 study by Oscar Bergman and colleagues at the Stockholm School of Economics found that the anchoring effect decreased with higher cognitive ability but did not vanish.

Has anchoring bias been replicated?＋

The basic effect has. In the Many Labs project, published in 2014, 36 independent samples with 6,344 participants in total re-ran 13 classic effects, and the four anchoring questions were among the very large effects. Some striking variations are less certain: a 2014 paper by Zacharias Maniadis, Fabio Tufano and John List urged caution about early anchoring results in economic valuations until independent replications exist.

How can you avoid anchoring bias?＋

Warnings alone do little: a 1996 study by Timothy Wilson and colleagues found anchoring hard to avoid even when people were forewarned. What does help is considering the opposite, that is, listing reasons why the anchor might be wrong, which reduced the effect in experiments by Mussweiler, Strack and Tim Pfeiffer. Forming your own estimate before you see someone else's number, and knowing the relevant facts well, also help.