Judgment Is Prone to Bias
A reflection on cognitive bias, behavioural finance, and better investing inspired by Amos Tversky
“Judgment is prone to bias.”
— Amos Tversky
An editorial by Debaditya Chatterjee for INVSTORY.
Few thinkers have changed our understanding of decision-making as profoundly as Amos Tversky. Through his groundbreaking collaboration with Daniel Kahneman, he transformed cognitive psychology, behavioural economics, and ultimately behavioural finance. Their research challenged the long-held belief that people consistently make rational decisions, demonstrating instead that our judgments are shaped by predictable cognitive biases and mental shortcuts known as heuristics.
For anyone involved in the stock market, this insight is more than academic. It is practical.
Every trading decision, every investment strategy, and every portfolio allocation is made under uncertainty. Financial markets never provide complete information, yet our minds naturally seek certainty. We become attached to our forecasts, search for evidence that confirms our existing views, remember recent market events more vividly than long-term trends, and often mistake confidence for accuracy.
These behaviours are not signs of poor intelligence.
They are characteristics of human judgment.
Recognising them is one of the foundations of successful investing.
Behavioural finance teaches us that market success depends not only on technical analysis, fundamental analysis, valuation, or economic research. It also depends on understanding investor psychology, market psychology, risk management, and disciplined decision-making. The greatest investment opportunities can be overlooked because of fear, while unnecessary risks are often taken because of overconfidence.
One lesson the financial markets have reinforced throughout my own journey as a trader, investor, research analyst, and market educator is that experience alone does not eliminate bias. Experience simply gives us more opportunities to recognise it.
Every trading journal records numbers.
Every thoughtful trader also learns to record decisions.
Why was this position initiated?
What assumptions supported it?
Which facts were ignored?
What emotions influenced execution?
Questions like these gradually improve judgment, because they force us to examine our thinking before we evaluate our results.
The market itself is remarkably objective.
Prices move according to countless forces beyond any individual’s control.
Our responsibility is not to control the market.
Our responsibility is to improve the quality of our own decisions.
That requires intellectual humility, continuous learning, evidence-based investing, disciplined execution, and the willingness to change our views whenever new information emerges.
This is the enduring relevance of Amos Tversky’s work.
He reminded us that the greatest risks in financial markets are not always external.
Very often, they originate within our own minds.
The trader who recognises cognitive bias before entering a position gains an advantage that no indicator, algorithm, or prediction can consistently provide.
Because successful investing begins long before capital is committed.
It begins with disciplined thinking.
Final Reflection
Financial markets reward preparation more often than prediction.
They reward discipline more often than certainty.
Amos Tversky’s work continues to remind traders and investors that better decisions begin with better judgment. The more aware we become of our own biases, the more objective our investment decisions become.
In the end, lasting success in the markets is achieved not simply by analysing price—but by understanding the mind that interprets it.
Editorial written by Debaditya Chatterjee for INVSTORY.