CODEXCard 1 of 8 · Core Cognitive Biases
Anchoring bias
The first number sets the gravity.
Anchoring bias describes how an initial number, once heard, quietly shapes the judgments that follow. Ask people to estimate a price, a salary or a quantity after showing them a figure, and their answers cluster near that figure. It does not matter whether the starting point was meaningful. It only has to come first.
Kahneman and Tversky documented the effect in the 1970s, and in Thinking, Fast and Slow Kahneman explains it with two mechanisms. The slow, deliberate mind starts at the anchor and moves away from it, but stops early, as soon as the answer feels plausible. The fast mind, meanwhile, is primed by the anchor and starts recalling evidence that fits it. Both routes push the final estimate toward the opening number.
The common mistake is believing that knowing about anchoring makes you immune. It does not. Experts, judges and experienced negotiators all show the effect, and paying close attention in the moment changes little. What works is structure: decide your walk-away price, your estimate or your offer in writing before the conversation starts, so the anchor has nothing soft to land on.
Anchoring often travels with framing. Whoever sets the first number also sets the frame for what counts as generous, reasonable or extreme, which is why moving first can be an advantage.
Example
You are shopping for a used car and the seller opens at a figure well above what similar cars sell for. Even though you suspect the price is inflated, a counteroffer a little below it starts to feel bold. If you had checked recent sale prices and written down your limit at home, the opening figure would carry far less weight.
Try it this week
Before your next negotiation or estimate, write your own number on paper before you look at or listen to anyone else's.
From Core Cognitive Biases (Daniel Kahneman · 2011).
