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NISM-Series-X-B: Investment Adviser (Level 2) · Basics of Behavioural Finance

Cognitive Biases: Belief Perseverance and Information-Processing Errors

Updated 11 October 2026 · Fact-checked

Cognitive biases are systematic errors in how investors think, not how they feel. They fall into two groups: belief perseverance biases, where you cling to existing views, and information-processing biases, where you handle data badly. To solve questions, match the investor's behaviour to the right bias label.

Understand Cognitive Biases

Cognitive biases come from faulty reasoning, memory or statistics. They are different from emotional biases, which come from feelings, impulses or intuition. The usual exam framing: cognitive errors are easier to correct with better information and education. Emotional biases are harder to fix, so an adviser often adapts the advice to them.

Cognitive biases are split into two groups. Belief perseverance biases are about holding on to a view after new evidence appears. They include cognitive dissonance, conservatism, confirmation, representativeness, illusion of control and hindsight. Information-processing biases are about how data is used or weighed. They include anchoring and adjustment, mental accounting and framing, and availability.

Know each one in a line. Overconfidence: you overrate your knowledge or skill, so you trade too much and diversify too little. It is generally treated as an emotional bias, though it has cognitive roots, so it is not a member of either cognitive group. Cognitive dissonance: you feel discomfort when facts clash with your beliefs or past choices, so you ignore or explain away the facts. Anchoring: you fix on a reference number, such as your purchase price or a past high, and adjust too little. Representativeness: you judge by resemblance to a familiar type, for example assuming a recent winning fund will keep winning. Availability: you judge likelihood by how easily an example comes to mind, such as a recent news story. Confirmation: you seek and favour information that supports your view and ignore the rest. Hindsight: after the outcome, you feel you knew it all along. Conservatism: you update beliefs too slowly. Illusion of control: you think you can influence outcomes you cannot.

The key skill is spotting the trigger word in the case. Words like 'recent news' point to availability. 'Original price' or 'target of ₹500' point to anchoring. 'Similar to' or 'looks like' point to representativeness. 'Only reads reports that agree' points to confirmation. 'I knew it' points to hindsight.

Key formulas to remember

Cognitive vs emotional
Cognitive = faulty reasoning (correctable by information); Emotional = feelings or impulse (hard to correct)
Exams often ask which type an adviser should try to correct and which to accommodate.
Belief perseverance group
Cognitive dissonance, Conservatism, Confirmation, Representativeness, Illusion of control, Hindsight
Common core of this group is clinging to existing beliefs.
Information-processing group
Anchoring and adjustment, Mental accounting, Framing, Availability
Common core is faulty handling or weighting of data.
Overconfidence effects
Overconfidence → excess trading + under-diversification + underestimated risk
Typical consequence statements in options. Overconfidence is generally treated as an emotional bias.

How to solve Cognitive Biases questions

Use this method for any question on cognitive biases.

  1. 1Read the scenario and underline the investor's behaviour, not the outcome.
  2. 2Ask: is this a feeling (emotional) or a reasoning or data error (cognitive)?
  3. 3If cognitive, ask: is the investor holding on to a belief, or mishandling information?
  4. 4Look for trigger words: recent news, reference price, resemblance, only supporting data, 'I knew it'.
  5. 5Match the trigger to one bias and eliminate options with similar-sounding ones.
  6. 6If asked for advice, pick education, data, and structured process for cognitive biases.
  7. 7Re-check that your chosen label fits the behaviour, not just a keyword.

Quickest way: Trigger-word matching

When to use it: Use when you have under a minute and the question asks you to name the bias.

  1. Recent event or vivid story: availability.
  2. Fixed number such as purchase price: anchoring.
  3. Looks like a past winner: representativeness.
  4. Seeks agreeing views only: confirmation.
  5. Says 'I knew it all along': hindsight.
  6. Rates own skill too high, trades often: overconfidence.
  7. Slow to change view on new data: conservatism.

Common mistakes in Cognitive Biases

  • Confusing anchoring with availability.

    Both involve information that influences a decision.

    Fix: Anchoring uses a specific reference number. Availability uses how easily an example comes to mind.

  • Labelling confirmation bias as conservatism.

    Both keep the old belief alive.

    Fix: Confirmation is about selecting supporting evidence. Conservatism is about updating too slowly.

  • Treating emotional biases as cognitive.

    Overconfidence looks like a reasoning error because it involves misjudging your own skill.

    Fix: Overconfidence is generally treated as an emotional bias, though it has cognitive roots. It does not belong to the belief perseverance or information-processing groups.

  • Mixing representativeness with hindsight.

    Both involve patterns and past events.

    Fix: Representativeness predicts by resemblance. Hindsight claims after the fact that the outcome was obvious.

  • Choosing the outcome rather than the behaviour.

    Case studies describe losses, which pull attention to emotions.

    Fix: Name the bias from the thinking process described, not from the result.

Worked examples

Example 1

An investor refuses to sell a stock at ₹300 because he bought it at ₹500 and wants to 'at least get back to ₹500'. Which bias is most evident? (A) Availability (B) Anchoring (C) Hindsight (D) Representativeness

Show the solution
  1. The behaviour: decision tied to the purchase price of ₹500.
  2. A fixed reference number driving the decision points to anchoring.
  3. Availability needs a recent vivid event. None is given.
  4. Hindsight needs a claim of having known the outcome. None is given.
  5. Representativeness needs resemblance to a type. None is given.

Answer: (B) Anchoring

Example 2

After a market fall, a client says, 'I always knew this crash was coming.' His portfolio records show no sell or hedge action before the fall. Which bias, and what is the adviser's best response? (A) Confirmation; ignore it (B) Hindsight; show his records and the documented, forward-looking plan (C) Conservatism; raise equity (D) Availability; avoid news

Show the solution
  1. The client claims after the event that the outcome was predictable.
  2. That is hindsight bias.
  3. His records show no sell or hedge action before the fall, so they suggest he did not act on any foresight. The adviser should raise this tactfully, using the records and the written plan, and not as a challenge to the client.
  4. Hindsight is cognitive, so the fix is information and evidence.
  5. Option B pairs the right bias with an information-based response.

Answer: (B) Hindsight; show his records and the documented, forward-looking plan

Exam tips

  • Learn the two groups and the members of each. Group questions are common.
  • Remember that cognitive biases are corrected with information, while emotional biases are usually accommodated.
  • Read carefully for trigger words, then check against similar bias options.
  • With negative marking, skip only if two options remain equally plausible after the trigger-word check.
  • Expect case-style questions where the adviser must choose a response matching the bias type.

Practice questions from Basics of Behavioural Finance

Cognitive Biases in other exams

The same ground in other exams, if you are preparing for more than one or want another angle on it.

Cognitive Biases: frequently asked questions

What is the difference between anchoring and availability bias?

Anchoring means fixing on a specific reference value, such as a purchase price, and adjusting too little. Availability means judging how likely something is by how easily an example comes to mind, such as recent news.

Is overconfidence a cognitive or emotional bias?

It is generally treated as an emotional bias, though it has cognitive roots. It comes from overrating one's own knowledge or skill. It often leads to excess trading and poor diversification.

What are belief perseverance biases?

These are biases where an investor clings to an existing belief despite new evidence. Examples are cognitive dissonance, conservatism, confirmation, representativeness, illusion of control and hindsight.

How should an adviser deal with cognitive biases?

Because they stem from reasoning errors, education, data and a structured process usually help. This differs from emotional biases, where the adviser often adapts the plan instead.