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Cognitive biases

IB Psychology · 2027 Syllabus

Inquiry Question & Thinking Prompt

  • Why is it so incredibly difficult for a human being to admit they are wrong, even when presented with undeniable facts?
  • How does our brain's desire to save mental energy (being a "cognitive miser") make us vulnerable to manipulation by marketers and salespeople?
  • Can simply learning about cognitive biases actually prevent you from falling victim to them in the future?

Learning Objective

To understand how heuristics lead to predictable errors in thinking.

📖 Definition / Conceptual Understanding

Cognitive biases are systematic pattern of deviation from rationality or objectivity in thinking, judgment and decision making which are predictable when people rely on heuristics (mental shortcuts) to process information and make rapid decisions.
Confirmation bias refers to the cognitive tendency to seek out, interpret, favour, and recall information to support one’s pre existing beliefs or hypotheses, while simultaneously ignoring and undervaluing evidence that contradicts these beliefs rather than objectively evaluating all available evidence.
Anchoring bias refers to the tendency to rely too heavily—or "anchor"—on the very first piece of information offered when making decisions or estimates, even when that information is irrelevant and arbitrary. Once an anchor is set, people tend to adjust their judgements insufficiently away from it, meaning their final decision remains biased toward the initial anchor.

⚙️ Mechanism / Explanation

Cognitive bias results because we rely on System 1 thinking. To save cognitive energy, we use heuristics (shortcuts) instead of rational System 2 analysis.
Confirmation bias creates an "echo chamber" in the mind, protecting our ego and saving us the mental strain of having to rewrite our schemas (accommodation). It lead individuals to construct a skewed and overly confident view of reality, often resulting in poor or irrational choices.
Anchoring bias takes place especially when we are uncertain about a value, System 1 uses the initial number (the anchor) as a starting point. We then adjust away from the anchor, but because System 2 is lazy, we usually stop adjusting way too soon, leading to an inaccurate final judgment.

📌 Other Relevant Information

Cognitive biases are systematic deviations from rationality in judgment. They are the direct consequence of humans acting as "cognitive misers." Because our environment is flooded with an overwhelming ocean of data, our brains must use heuristics—fast, automatic System 1 shortcuts—to make sense of the world. While usually efficient, these shortcuts cause predictable errors.
Confirmation bias occurs because processing information that contradicts our existing schemas causes psychological discomfort (cognitive dissonance) and requires heavy mental effort to resolve. To avoid this, our brain selectively filters reality to confirm what we already know.
Anchoring bias occurs during numerical estimations. When exposed to an initial, arbitrary value (the anchor), our brain subconsciously uses it as a reference point. Even if we know the anchor is entirely random, its presence skews our final estimation toward that initial number because our subsequent mental adjustments are almost always insufficient.

🃏 Scenarios

Select a scenario to read it, then click the card to reveal the explanation. Each scenario feeds directly into a Paper 1B practice question.

Scenario 1: The Echo Chamber (Confirmation Bias)
Scenario: You firmly believe that a certain brand of smartphone is the absolute best on the market. When it’s time to buy a new phone, you search YouTube for "Why Brand X is the best phone" and watch three glowing reviews. When a friend sends you an article titled "Major Battery Flaws in Brand X," you quickly skim it and dismiss the author as a "hater" who doesn't know what they are talking about.
Question: Using your knowledge of Confirmation Bias, explain the cognitive process that led to your behavior.
Click to reveal
  1. Selective Seeking: Your search query ("Why Brand X is the best") actively sought out information that already matched your pre-existing schema, rather than neutrally searching "Brand X reviews."
  1. Selective Interpretation: When faced with disconfirming evidence (the battery flaw article), your brain experienced cognitive strain. To protect your existing belief, you dismissed the source as biased ("a hater") rather than engaging with the objective facts.
  1. The Result: You remain highly confident in your belief, completely unaware that your System 1 has artificially filtered out half of reality.
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🔬 Common Studies

These studies feed directly into Paper 2B practice questions.

📋 What is Required

Paper 1A— Short answer (4 marks)
Describe one cognitive bias with reference to one study.
View mark scheme
9 marks: Accurate description of bias and study with a clear link.
Paper 1B— Scenario response (6 marks)
Evaluate research on one cognitive bias.
View mark scheme
22 marks: Detailed knowledge, evaluation of research, critical thinking.

💬 ATL Discussion & Theory of Knowledge

ATL Discussion Questions

Factual
What is a cognitive bias?
Conceptual
How do heuristics help and hinder survival?
Debatable
Are humans fundamentally irrational thinkers?

Link to Theory of Knowledge

If our brains are naturally wired to seek out information that validates our pre-existing beliefs (and ignore information that contradicts them), to what extent is it possible for any human being to be truly objective? Is our perception of "reality" just a reflection of what we already want to believe?

🔗 Link to Concepts

Select a concept to explore how it connects to this topic. These connections also feed into Paper 1C practice questions.

Link to Measurement

The Link: How can psychologists accurately measure the extent to which a cognitive bias has distorted someone's thinking?
Application: Because the internal mechanisms of System 1 are unconscious, researchers must measure cognitive bias indirectly by quantifying the behavioral output. In anchoring studies, the bias is mathematically measured by the distance between the final estimate and the original anchor. In confirmation bias studies (like Wason's 2-4-6 task), it is measured by counting the frequency of confirming questions asked versus disconfirming questions asked.
Since we can only measure the final behavioral output, how can researchers be absolutely certain they are measuring an unconscious cognitive bias, rather than simply measuring a participant's lack of motivation or mathematical uncertainty?

🧠 Quick Quiz

What is the primary definition of a cognitive bias?

Cognitive biases occur when the brain uses which of the following to simplify information processing?

Which of the following is a characteristic of cognitive biases?

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