41 lessons in the app

Cognitive biases, with an everyday example of each

A cognitive bias is a predictable way judgment drifts from what the evidence supports: the first number you hear pulls your estimate, money already spent pulls your next decision. Below are the biases Scroll's lessons cover, each with the study that named it.

Try 4 lessons exactly as they appear in the app

Psychology40s read

Lesson 1 of 4

Confirmation Bias

Your brain has a full-time job: making you feel right. Confirmation bias is the tendency to search for, interpret, and remember information that confirms what you already believe, and ignore everything that doesn't. It's the reason two people can read the same article and come away with opposite conclusions.

Source Wason, P.C. (1960). On the failure to eliminate hypotheses in a conceptual task.

Quick quiz

A researcher reads only studies that support their hypothesis while ignoring contradicting evidence. This demonstrates:

Psychology40s read

Lesson 2 of 4

Anchoring Bias

The first number you hear sets an invisible anchor. In negotiations, whoever names a price first shapes the entire conversation. Judges given random numbers before sentencing give harsher or lighter sentences accordingly. Your brain uses the anchor as a reference point even when it is completely irrelevant.

Source Tversky, A., & Kahneman, D. (1974). Judgment under Uncertainty: Heuristics and Biases.

Quick quiz

In a salary negotiation, who benefits most from the anchoring effect?

Psychology40s read

Lesson 3 of 4

The Sunk Cost Fallacy

You stay in a bad movie because you paid for the ticket. You keep a failing project alive because you invested years. The money or time is gone regardless. It is a sunk cost. Rational decisions look forward, not backward. But our brains hate "wasting" past investments, even when continuing wastes more.

Source Arkes, H.R., & Blumer, C. (1985). The psychology of sunk cost.

Quick quiz

You have invested two years in a project that is clearly failing. The rational decision is to:

Psychology38s read

Lesson 4 of 4

The Halo Effect

Attractive people are assumed to be smarter, more competent, and more trustworthy, even by judges and juries. This is the halo effect: one positive trait (like looks) casts a warm glow over unrelated attributes. It works in reverse too, one flaw can contaminate your entire impression of someone.

Source Thorndike, E.L. (1920). A constant error in psychological ratings.

Quick quiz

A job candidate who is attractive is rated as more competent despite no evidence of their skills. This is an example of:

37 more lessons like these in the app

Every title here is a lesson in Scroll, with its own quiz. Five a day are free; Premium has no daily limit.

The Dunning-Kruger Effect
Loss Aversion
The Spotlight Effect
The Mere Exposure Effect
Negativity Bias
The Availability Heuristic
The Bandwagon Effect
The Framing Effect
The Endowment Effect
Fundamental Attribution Error
The Actor-Observer Bias
Self-Serving Bias
The IKEA Effect
Status Quo Bias
The Barnum Effect
The Contrast Effect
The Decoy Effect
Hindsight Bias
The Planning Fallacy
The Ostrich Effect
The Narrative Fallacy
The Identifiable Victim Effect
Normalcy Bias
Choice-Supportive Bias
In-Group Bias and Out-Group Hostility
Implicit Bias: The Unconscious Prejudice
The Expertise Trap
The Sunk Cost Fallacy in Business
The Endowment Effect: Why Owners Overvalue
Status Quo Bias: Why Default Wins

Show all 37 titles

Home-Country Bias
Sunk Cost Fallacy in Investing
Loss Aversion and Your Portfolio
Recency Bias: The Market Always Feels Like Now
Overconfidence: The Most Expensive Bias
The Planning Fallacy
Survivorship Bias and Productivity Advice

About cognitive biases

What is a cognitive bias?

A systematic error in thinking: a pattern in how people judge or decide that departs from what the evidence supports, in the same direction, across many people. Anchoring and confirmation bias are two of the best studied.

How many cognitive biases are there?

There's no fixed number. Popular lists run to well over 100 entries, but many overlap or describe the same effect under different names, and the evidence behind them varies a lot. Scroll's lessons cover the ones with a named study behind them.

Can you get rid of cognitive biases?

Not entirely. Knowing a bias's name doesn't make you immune to it. What tends to help is changing the situation: writing down an estimate before you see an anchor, or deciding what evidence would change your mind before you look.

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