IB Syllabus focus: 'Anchoring and confirmation bias influence decision-making and are key applications of cognitive psychology.'
Cognitive biases are systematic thinking patterns that can distort judgment. In IB Psychology, anchoring and confirmation bias are important examples because they show how seemingly rational decisions are often shaped by prior information and selective thinking.
Cognitive biases in decision-making
The cognitive approach argues that decision-making depends on how people process information. This means errors in judgment are often not random. Instead, they follow predictable patterns. Cognitive biases are useful for psychologists because they help explain why people may make poor, inaccurate, or one-sided decisions even when they have enough information.
Cognitive bias
A cognitive bias is a systematic pattern of thinking that leads people to judge information or make decisions in a distorted or less accurate way.
Cognitive biases often occur because the brain tries to simplify complex information. This can save time, but it can also reduce accuracy. Two of the most important biases in this subtopic are anchoring bias and confirmation bias.
Anchoring bias
Anchoring bias is the tendency to rely too heavily on an initial piece of information when making a judgment or decision.
With anchoring, the first number, idea, or impression acts as a reference point. Later judgments are then made by adjusting away from that starting point, but the adjustment is usually too small. As a result, the final decision remains too close to the original anchor.
A classic study by Tversky and Kahneman (1974) demonstrated this effect. Participants saw a wheel of fortune rigged to stop at either a low or high number. They were then asked whether the percentage of African countries in the United Nations was higher or lower than that number, and to estimate the true percentage. Their estimates were influenced by the random number, even though it was clearly irrelevant. This shows that even arbitrary anchors can shape judgment.
Anchoring matters in many real-life decisions:
Consumer behavior: the first price seen can shape what seems cheap or expensive.
Negotiation: the opening offer can influence the final settlement.
Medicine: an early diagnosis may bias later interpretation of symptoms.
Law: suggested sentences or damages can influence later judgments.
Anchoring is powerful because people often assume the first information they receive is meaningful. It reduces uncertainty, but it may also narrow thinking too early.
Confirmation bias
Confirmation bias is the tendency to seek, interpret, and remember information in ways that support existing beliefs or expectations.
In decision-making, confirmation bias means people do not evaluate evidence in a fully balanced way. Instead, they pay more attention to information that fits what they already think and may ignore, dismiss, or undervalue contradictory evidence.
A well-known example comes from Wason’s rule-discovery task.
This diagram shows the classic Wason selection task, where the goal is to test a conditional rule by choosing which cards to turn over. Many people choose cards that could confirm the rule (verification) rather than those that could disprove it (falsification), which makes it a useful visual analogy for confirmation bias in evidence testing. Source
Participants were given the sequence 2-4-6 and asked to identify the rule. Many tested examples that confirmed their guesses rather than trying to disprove them. This often prevented them from finding the correct rule quickly. The task showed that people prefer confirming evidence over disconfirming evidence, even when disconfirmation would be more useful.
Confirmation bias affects many decisions:
choosing which news or sources to trust
judging whether a person is honest or intelligent
evaluating medical or health claims
making political or social judgments
deciding whether an investment or plan is still good
This bias can be especially strong when a person is emotionally committed to a belief. In that case, information processing becomes less objective and more defensive.
How these biases shape decision-making
Anchoring and confirmation bias influence different stages of decision-making.
Anchoring mainly affects the starting point of judgment.
Confirmation bias mainly affects the search for and evaluation of evidence after that starting point.
Together, they can strongly distort decisions. A person may begin with an early anchor, then selectively gather evidence that supports it. This makes the original judgment feel increasingly certain, even if it was weak from the start.
Important cognitive processes involved include:
selective attention to some information over others
selective interpretation of ambiguous evidence
memory bias, where supportive information is recalled more easily
insufficient adjustment away from an initial anchor
overconfidence, because repeated confirmation can make beliefs seem stronger than they are
These biases help explain why people may persist with incorrect choices. They also show that decision-making is often influenced by how information is framed and processed, not only by the quality of the information itself.
Evaluating cognitive bias explanations
Research on anchoring and confirmation bias is a strong application of cognitive psychology because it is usually based on controlled experiments. This allows researchers to isolate variables and show clear cause-and-effect relationships. For example, changing the anchor can change later estimates, and changing the way evidence is searched can alter conclusions.
However, there are limitations. Many studies use simplified laboratory tasks, so real-life decision-making may be more complex. In everyday settings, people are also influenced by experience, emotions, social pressure, and motivation. The size of a bias may vary depending on expertise, time pressure, and how important the decision is.
Even so, these biases remain highly useful concepts because they are:
replicable
practical
relevant to many settings where judgments matter
Reducing the impact of bias
Psychologists and decision-makers try to reduce bias by using structured methods.
Useful strategies include:
making an independent estimate before hearing others’ opinions
deliberately searching for evidence that disproves an initial belief
using checklists or fixed decision criteria
asking another person to act as a devil’s advocate
reviewing evidence in a more systematic and less emotional way
These methods do not remove bias completely, but they can improve the quality of decisions by slowing down automatic thinking and encouraging more balanced judgment.
FAQ
A starting point becomes a bias when it affects judgment more than it should.
Using prior information is not automatically irrational. For example, last year’s price may be a useful reference. Anchoring becomes problematic when:
the starting information is irrelevant
it is given too much weight
people fail to adjust enough from it
So, anchoring is not about having a starting point at all. It is about overrelying on one.
Expertise can reduce bias, but it does not eliminate it.
Experts often work quickly under pressure, which can increase reliance on mental shortcuts. They may also become more confident in their judgments, which can strengthen confirmation bias. In some cases, expertise even makes people better at defending a mistaken belief rather than correcting it.
This is why structured decision procedures are often used in medicine, law, and finance.
Yes. They can reinforce each other.
For example:
an early number, impression, or diagnosis acts as an anchor
later information is then interpreted in ways that support that anchor
contradictory evidence may be ignored or discounted
This combination can make a decision seem highly convincing even when it rests on weak initial information. That is one reason early judgments can be so influential.
Digital environments often make confirming information easier to find.
Online users can:
follow sources they already agree with
search using belief-based keywords
receive algorithmic recommendations that match prior interests
avoid challenging viewpoints with a single click
This can create a feedback loop where the same belief is repeatedly supported. Repetition may then increase confidence, even if the evidence quality is poor.
Awareness helps, but bias often operates automatically.
People may recognize the concept in general but still believe their own judgment is objective in the moment. This is sometimes called a “bias blind spot.” Also, when a decision is emotionally important, motivation can overpower awareness.
Bias reduction usually works better when knowledge is combined with procedures, such as blind review, checklists, or forced consideration of alternatives.
Practice Questions
Outline one characteristic of confirmation bias in decision-making. [2 marks]
1 mark for identifying that confirmation bias involves seeking, interpreting, or remembering information that supports an existing belief.
1 mark for linking this tendency to decision-making or judgment.
Explain how anchoring bias may influence decision-making, using one relevant study. [6 marks]
1 mark for identifying anchoring bias as reliance on an initial piece of information.
1 mark for explaining that later judgments are adjusted from this starting point.
1 mark for explaining that adjustment is often insufficient.
1 mark for describing one relevant study, such as Tversky and Kahneman (1974).
1 mark for accurately stating the study’s findings, such as higher anchors producing higher estimates.
1 mark for clearly linking the findings to how decisions can be distorted in real judgments.
