In a classic experiment, Daniel Kahneman and Amos Tversky spun a rigged wheel that landed on either 10 or 65, then asked participants to estimate the percentage of African countries in the United Nations. Despite the number being random and clearly unrelated, participants who saw 65 gave estimates almost twice as high as those who saw 10.
Why Irrelevant Numbers Still Move Us
The brain treats the first number it encounters as a reference point, then adjusts from there — but the adjustment is usually insufficient, leaving the final estimate biased toward the anchor.
Where This Shows Up
Salary negotiations, real estate listing prices, and ‘original price’ tags before a discount all exploit anchoring. The first number presented frames every number that follows.
Defending Against It
Deliberately generating your own independent estimate before hearing any external number, and explicitly asking ‘would I believe this if the anchor were different,’ both measurably reduce the bias in controlled studies.
