Psychologie a chování
Cognitive Biases: 12 Traps of the Investor's Mind
Key takeaways
- Cognitive biases are unconscious mental shortcuts that work in an evolutionary context but fail in markets.
- Every investor is subject to some biases — the key is to recognise them, not eliminate them.
- The most common traps are overconfidence, recency bias, anchoring, confirmation bias, and herd mentality.
- Systematic approaches (automated investing, a fixed plan, passive strategies) reduce the room for biases.
Cognitive biases are systematic patterns of flawed thinking in which the brain resorts to mental shortcuts instead of full analysis. In everyday life they help us survive — in markets they can cost years of returns.
Biases affecting information selection
- Confirmation bias: We seek out information that confirms what we already believe and ignore counter-arguments. An investor convinced of an impending crash reads only negative analyses.
- Availability bias: We assign greater weight to what we can easily recall — recent events or dramatic stories.
- Recency bias: We overweight recent developments at the expense of the long-term average. Covered in more detail in this article.
Biases affecting the assessment of value
- Anchoring: We cling to the first value we saw (the purchase price of a stock) and judge everything against it, even when it is irrelevant.
- Mental accounting: We divide money into separate buckets and treat each differently. Covered in detail in the article on mental accounting.
- Sunk cost fallacy: We continue an investment solely because we have already invested time or money — not because it makes sense.
Biases affecting self-assessment
- Overconfidence: We overestimate the accuracy of our forecasts and our ability to beat the market.
- Self-attribution bias: We attribute gains to our skill and losses to bad luck or the market.
- Illusion of control: We believe that by monitoring frequently or trading actively we have greater control over outcomes.
Biases affecting group behaviour
- Herd mentality: We do what we see others doing — buying when everyone buys and selling in panic with the crowd.
- FOMO: Fear of missing out drives purchases at the top of a rally, when "everyone is making money."
A shared defence
Systematic measures — automated investing, a fixed plan, rules against impulsive trades — reduce the room for most biases at once. You don't need to be a psychologist; it is enough to set up a system that protects you even when your brain fails.
FAQ
What are cognitive biases in investing?
Systematic patterns of flawed thinking in which the brain resorts to mental shortcuts. In markets they lead to poor decisions — buying at the top, selling in panic, ignoring counter-arguments.
Which cognitive biases are most costly?
Overconfidence, recency bias (overweighting recent developments), herd mentality, and anchoring (clinging to the purchase price) — all repeatedly show up even in experienced investors.
How do you defend against cognitive biases?
They cannot be eliminated entirely, but they can be circumvented with a system. Automated investing, a fixed plan with rebalancing and selling rules, a waiting rule for impulsive reactions — all of these reduce the room for biases.