The Anchoring Bias: How a Single Number Can Skew Your Judgment

The First Number Wins Picture this: you’re shopping for a jacket. The first one you see costs £600. The next, £300. Suddenly, that second one feels like a bargain—even if you’d never normally spend that much. That’s anchoring bias in action: our tendency to rely too heavily on the first piece of information (the “anchor”) when making decisions. First studied by psychologists Amos Tversky and Daniel Kahneman in 1974, this bias explains why initial numbers—prices, salaries, statistics—can shape judgment far beyond reason. Once the anchor is set, the brain adjusts only slightly, even when it knows better.

How Anchoring Hijacks the Mind

Anchoring works because the brain loves shortcuts. When faced with uncertainty, we subconsciously grab onto whatever reference point is available. In one famous experiment, participants spun a rigged “wheel of fortune” that landed on either 10 or 65, then were asked if the percentage of African countries in the United Nations was higher or lower than that number. Those who saw 10 guessed 25%; those who saw 65 guessed 45%. The random number, completely irrelevant, had still pulled their answers toward it. Even meaningless anchors reshape our sense of scale.

Everyday Anchors You Don’t Notice

Anchoring affects far more than shopping. Negotiations are prime examples: the first offer—high or low—frames every counteroffer that follows. In salary discussions, the opening number can determine thousands in eventual pay. Real estate listings, too, exploit anchoring; homes priced higher initially tend to sell for more, regardless of their intrinsic value. Psychologists have even observed “self-anchoring,” where people base their confidence on early assumptions (“I’m probably not qualified for this job”) and unconsciously limit their performance to fit that belief.

The Brain’s Rationalization Trick

Once an anchor lodges, the prefrontal cortex kicks in to rationalize it. The brain doesn’t question the anchor—it defends it by generating supporting reasons. This phenomenon, known as selective accessibility, means we unconsciously search for evidence that justifies the first number we saw. That’s why discounts and “original price” tags are so persuasive—they turn cognitive bias into a marketing weapon.