The first number sticks: anchoring
A number you see first pulls your estimate towards it, even when it is plainly irrelevant. Learn to spot anchors in prices, offers and forecasts, and set your own.
PsychologyThink clearlyAbout 6 min: 4 reading, 2 practiceUpdated
Educational, not medical or mental-health advice.
- Explain what an anchor is and how it shifts estimates
- Spot anchors in prices, negotiations and forecasts
- Use "consider the opposite" and your own estimate first to weaken an anchor
Builds toward: Think clearly. Catch common thinking errors in yourself and in other people's arguments, and make better calls when you can't be sure.
Think clearly: thinking errors and better decisions: lesson 2 of 7
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Pairs with Tversky and Kahneman (1974), "Judgment under uncertainty: Heuristics and biases", the section on anchoring; OpenStax, Psychology 2e, section 7.3 "Problem Solving"
What it is
Anchoring is the pull of a starting number. When you estimate an unknown amount after seeing a number, your answer tends to stay too close to that number, even when you know it has nothing to do with the question.
In Tversky and Kahneman's 1974 experiment, a wheel of fortune was set to stop at either 10 or 65. People first said whether the share of African countries in the United Nations was higher or lower than that number, then gave their own estimate. The group that saw 10 gave a median estimate of 25%; the group that saw 65 said 45%. A spin of a wheel moved their answers by 20 points.
Quick check
Tap an answer to check it.
Before you guess how old a tree is, someone asks: "Is it older or younger than 1,200 years?" What happens to your guess?
- Anchors work even when people know they are arbitrary
Show answer
It is likely to be higher than if they had asked about 120 years. The number you are asked to compare with becomes a starting point, and estimates stay close to it.
Why it matters
Anchors are everywhere numbers are:
- Prices. "Was 899, now 499" makes 499 feel cheap, whatever the item is worth. A menu with one very expensive dish can make the others look reasonable.
- Negotiations. In studies of negotiation (Galinsky and Mussweiler, 2001), the first offer strongly predicted the final price, and whoever made it tended to do better.
- Experts too. In a study by Northcraft and Neale (1987), estate agents valued the same house after touring it, but each was given a different "asking price". Their valuations moved with the asking price, yet few of them listed it among the things they had used.
- Forecasts and plans. Last year's figure, or the first estimate someone said in a meeting, becomes the anchor everyone adjusts from, usually not far enough.
Unlike some famous findings, anchoring has held up well: a large project repeating classic studies in many labs at once (Klein and colleagues, 2014) found strong anchoring effects.
Worked example
You're selling your bike. A buyer opens: "I'll give you 120." You had hoped for 250.
- Notice the anchor. 120 is now the reference point. If you simply bargain up from it, you may settle near 160 and feel you did well.
- Go back to your own estimate, made before you heard theirs. You checked similar bikes online: they sell for 220 to 270.
- Consider the opposite. Ask: what reasons are there that the bike is worth more than 120? New tyres, recent service, a lock included. Saying these out loud weakens the pull of their number.
- Re-anchor. Reply with your own figure and reasons: "Similar bikes sell for around 250, and this one has new tyres. I can do 240."
Better still, next time make the first offer yourself, with a figure you can justify.
Common mistake
Thinking an anchor only works if you believe it. The wheel-of-fortune number was obviously random, and it still moved people's answers. "I know that price is silly, so it won't affect me" is exactly when it does.
Key terms
- anchor
- a starting number that pulls later estimates towards it
- anchoring
- the tendency for estimates to stay too close to a starting number
- adjustment
- moving away from the anchor, which people usually do too little
- consider the opposite
- listing reasons the true value could be far from the anchor, which weakens its pull
Practise the key terms
Tap a card to turn it over. 4 cards.
| Front | Back |
|---|---|
| anchor | a starting number that pulls later estimates towards it |
| anchoring | the tendency for estimates to stay too close to a starting number |
| adjustment | moving away from the anchor, which people usually do too little |
| consider the opposite | listing reasons the true value could be far from the anchor, which weakens its pull |
Practice
Quick quiz
Tap an answer to check it.
In the 1974 study, what changed people's estimates of the share of African countries in the UN?
- Both groups were similar; only the wheel number differed
Show answer
Whether the wheel had stopped at 10 or at 65. The median estimate was 25% after seeing 10 and 45% after seeing 65.
A shop shows "RRP 300, our price 179". What is the 300 doing?
- A recommended price is the seller's number, not a measure of value
Show answer
Acting as an anchor that makes 179 feel like a bargain. Compare with what similar items actually sell for, not with the shop's reference price.
Which is the best defence against an anchor in a negotiation?
- Their number then becomes your anchor
Show answer
Decide your own estimate from evidence beforehand, and make the first offer if you can. Your own evidence-based number gives you a better starting point than theirs.
What did the estate agents in Northcraft and Neale's study report about the asking price?
- Few listed it at all
Show answer
Few listed it as something they had used, even though their valuations moved with it. Anchors work largely without our noticing.
Spot the error
One line is wrong. Tap it.
A friend explains how they budgeted for a trip. Which line shows anchoring?
- Listing costs is sound
- Comparing sources is sound
- A buffer is sensible planning
Show answer
"Last trip cost 900, so I started at 900 and added a bit.". Last year's total became the starting point. A new trip needs its costs built up from the new plan.
The other view
Anchoring is one of the sturdiest findings in decision research, but its size varies. It is strongest when people know little about the quantity, and weaker for things they know well. A few striking anchoring studies, such as those using the last digits of people's social security numbers, have been harder to repeat than the classic ones, so treat any single dramatic example with care.
In short
- An anchor is a starting number that pulls later estimates towards it, even when it is plainly random.
- In the 1974 wheel study, 10 led to a median estimate of 25%; 65 led to 45%.
- Anchors work on prices, negotiations, forecasts and experts, mostly without being noticed.
- Defences: make your own estimate first, consider the opposite, and make the first offer when you can.
- Anchoring has replicated well, but its size varies with how much people know.
Mastery check
Answer without looking back. Score 80% or more and the lesson is marked done. Your result is kept only in this browser.
Check yourself
Answer in your head first, then open the answer. Nothing is saved.
What is anchoring?
Show answer
The tendency for an estimate to stay too close to a number you saw first.
Name two places you are likely to meet anchors.
Show answer
Any two of: sale prices and "RRP" labels, the first offer in a negotiation, last year's figures in a budget or forecast, an expensive item on a menu.
Why should you make your own estimate before hearing someone else's number?
Show answer
So that your starting point comes from evidence, not from their number, which would otherwise pull your estimate towards it.
Further reading
- Tversky, A., & Kahneman, D. (1974). Judgment under uncertainty: Heuristics and biases. Science, 185(4157), 1124–1131.
- Northcraft, G. B., & Neale, M. A. (1987). Experts, amateurs, and real estate: An anchoring-and-adjustment perspective on property pricing decisions. Organizational Behavior and Human Decision Processes, 39(1), 84–97.
- Galinsky, A. D., & Mussweiler, T. (2001). First offers as anchors: The role of perspective-taking and negotiator focus. Journal of Personality and Social Psychology, 81(4), 657–669.
- Mussweiler, T., Strack, F., & Pfeiffer, T. (2000). Overcoming the inevitable anchoring effect: Considering the opposite compensates for selective accessibility. Personality and Social Psychology Bulletin, 26(9), 1142–1150.
- Klein, R. A., et al. (2014). Investigating variation in replicability: A "Many Labs" replication project. Social Psychology, 45(3), 142–152.
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