Psychology
The anchoring bias — why the first number wins
Once a number enters the room, every estimate after it drifts toward it — even numbers everyone knows are irrelevant. What the effect is, and the one thing that reliably weakens it.
1 min read
Ask someone to estimate a value right after showing them an unrelated number, and their answer shifts toward that number — even when they were told it was random.
Discovered by trying to break it
Tversky and Kahneman spun a wheel rigged to land on 10 or 65, then asked participants to estimate the percentage of African countries in the United Nations. Those who saw 65 guessed higher than those who saw 10 — despite knowing the wheel was arbitrary.
Where it costs the most
- Salary negotiations: the first figure named tends to set the range for everything that follows.
- Real estate: a high asking price pulls subsequent offers upward, even from buyers who researched comparable prices beforehand.
- Medical estimates: an anchor as trivial as a previous patient’s dosage can shift a clinician’s judgment.
What actually helps
Generating your own estimate before hearing anyone else’s number reduces — but does not eliminate — the pull. Anchoring survives even when people are paid to avoid it, which is part of why it counts among the most replicated effects in decision research.