The number that changes everything
How anchoring bias manipulates your decisions without you knowing it
🏷️ Categories: Decision making and biases.
It only takes one number to completely change your perception of reality.
Have you ever ended up buying something you didn’t need? Or accepted a negotiation offer you later regretted? Maybe it wasn’t entirely your decision. Maybe something happened beforehand, something that shifted your perception entirely.
That something has a name: anchor.
Today, we dive into the mind—right in that instant before a decision is made—to talk about anchoring bias (Tversky & Kahneman, 1974).
That phenomenon makes your estimate depend—heavily—on the first number you're shown.
Even if it’s absurd.
Even if it’s completely unrelated.
It shapes your perception afterward.
You'll see why seeing a "97" in a restaurant’s name makes you spend more, why a number in your ID can lead you to pay double for a bottle of wine, and why negotiating with someone who was “just suggesting a number” could cost you thousands.
Let’s begin.
1. What is Anchoring Bias?
Imagine this:
I ask you to calculate, in 5 seconds: 1 × 2 × 3 × 4 × 5 × 6 × 7 × 8
Then, I ask another group to calculate: 8 × 7 × 6 × 5 × 4 × 3 × 2 × 1
The result? The same: 40,320.
The estimated answers? Very different.
Those who started with 1 guessed around 512.
Those who started with 8 guessed around 2,250 (Tversky & Kahneman, 1974).
That’s anchoring bias.
The order of the information shifts your perception—even if it’s illogical or irrelevant. The term was introduced by Tversky and Kahneman in 1974 when they observed that people, when estimating, adjusted from an initial value—but did so incorrectly.
But it doesn't stop there...
2. Why Does Anchoring Happen?
One theory is the selective accessibility model (Mussweiler & Strack, 1997).
When you see a new number next to an anchor (your reference point), your mind retrieves information that matches that anchor.
For example, if you see something priced at €100, your brain starts looking for reasons to justify that price—without considering that you might find it for €25.
That €25 reasoning only comes much later.
Availability heuristic also kicks in: we consider things more likely if we can recall them easily (Tversky & Kahneman, 1974). If reasons why something should cost €100 come to mind quickly, that becomes the logical price.
A powerful combo—and very hard to resist.
3. How Does It Affect Us? Real-Life, Everyday Examples
Estimates
Two groups spun a rigged roulette wheel. One landed on 10, the other on 65.
Then they were asked: What percentage of UN countries are African?
Those who got 10 said 25%.
Those who got 65 said 45% (Tversky & Kahneman, 1974).
Price Negotiations
Students were asked to write the last two digits of their Social Security number next to pictures of products like wine or chocolate. Then, they had to state how much they'd be willing to pay.
The 20% of students with the highest digits (80–99) offered 216% to 346% more than those with the lowest digits (1–20) (Ariely, 2008).
Yes—our decisions can be that irrational.
(If you're curious, there are plenty more jaw-dropping experiments like this.)
Everyday Life
First impressions: They become the reference point for all future interactions. This affects interviews, judgments, politics...
School expectations: Teachers saw the same academic performance, but when told certain students were “gifted,” they evaluated them more positively—unconsciously biased (Darley & Gross, 1983).
Menus & product placement: The order of prices on a menu, shelf, or vending machine influences your choices without you noticing.
Jersey numbers: A player wearing number 94 instead of 54 was rated 6% better (Critcher & Gilovich, 2008).
Restaurant name: Studio 97 made people willing to pay $32.84 on average, compared to $24.58 for Studio 17 (Critcher & Gilovich, 2008).
Product model numbers: The P97 model led to higher estimated sales than the P17 (Critcher & Gilovich, 2008).
Marketing trick: A sign reading “Buy 18 chocolate bars” led to 38% more sales than one saying “Buy chocolate bars” (Wansink et al., 1998).
The most surprising part? The effect persists even after people forget the number.
That shows just how unconsciously anchoring works.
4. What Can We Do About It?
Not much. Even experts fall for anchoring bias (Englich et al., 2006).
But you can try to reduce its effect:
Find different reference points: Don’t settle for the first number you're given. If you're shopping, compare stores, similar products, and quality. If you're negotiating, research market data or historical price trends.
Question its actual relevance: Does that number really relate to your decision, or is it there just to sway you? Many times, the order or presence of certain data is strategically placed.
Delay the decision: Don’t decide in the heat of the moment. Anchoring works fast and impulsively. Postponing—even for a few minutes—can help cool off its influence.
Being aware of the bias doesn’t eliminate it—but it does weaken its grip.
And sometimes, that’s enough to make better choices.
✍️ Your Turn: What invisible “anchors” might be influencing your daily decisions without you realizing it? We’ve all overpaid for something at some point—just because we were comparing it to a higher initial price...
💭 Quote of the Day: "Human beings are poor examiners, subject to superstition, bias, prejudice, and a deep tendency to see what they want to see rather than what is actually there." — M. Scott Peck, The Road Less Traveled
See you next time! 👋
References 📚
Ariely, Dan (2008). Predictably Irrational.
Critcher, C. R., & Gilovich, T. (2007). Incidental environmental anchors. Journal Of Behavioral Decision Making, 21(3), 241-251. URL
Darley, J. M., & Gross, P. H. (1983). A hypothesis-confirming bias in labeling effects. Journal Of Personality And Social Psychology, 44(1), 20-33. URL
Englich, B., Mussweiler, T., & Strack, F. (2005). Playing Dice With Criminal Sentences: The Influence of Irrelevant Anchors on Experts’ Judicial Decision Making. Personality And Social Psychology Bulletin, 32(2), 188-200. URL
Strack, F., & Mussweiler, T. (1997). Explaining the enigmatic anchoring effect: Mechanisms of selective accessibility. Journal Of Personality And Social Psychology, 73(3), 437-446. URL
Tversky, A., & Kahneman, D. (1974). Judgment under Uncertainty: Heuristics and Biases. Science, 185(4157), 1124-1131. URL
Wansink, B., Kent, R. J., & Hoch, S. J. (1998). An Anchoring and Adjustment Model of Purchase Quantity Decisions. Journal Of Marketing Research, 35(1), 71-81. URL