Confirmation Bias
Seeking out information that supports a position while discounting evidence against it.
Also called: seeking confirmation
Written by Javier Sánchez Ros
In plain language
Once a position exists, the mind starts working for it. Supporting evidence feels compelling and contradictory evidence feels like noise.
It shows up as switching timeframes until one looks bullish, adding indicators until one agrees, and dismissing structure breaks as anomalies.
The defense is mechanical rather than psychological: define invalidation before entering, and let the level decide rather than your interpretation.
Worked through
A long position, and what gets read while it falls
- Bullish articles opened
- 7
- Bearish articles opened
- 0
- Timeframes checked
- until one looked up
- Stop
- moved down twice
The research is real and it is entirely one-directional. Every source consulted is chosen, unconsciously, for its likely conclusion, and each one that agrees makes the position feel better supported than it did an hour ago — while the position itself gets worse.
The timeframe search is the clearest tell. A trader who entered on the hourly chart and is now examining the weekly is not gathering information; they are looking for a chart on which the trade is still working, and on a long enough horizon there is always one.
What makes this expensive rather than merely irrational is that it operates on the exit. The stop was correct when it was set, and every piece of confirming evidence supplies a reason to move it — so a planned 1R loss becomes 3R by a series of individually defensible decisions.
The practical counter is to write the invalidation down at entry, in terms of price rather than narrative: "this idea is wrong below $47." A price cannot be reinterpreted by a bullish article.
Why it matters
Confirmation bias is what turns a small planned loss into a large unplanned one, by supplying reasons to ignore the exit you already set.
Common mistakes
- Changing the analysis timeframe after entry to justify holding.
- Adding indicators until one supports the position.
- Dismissing a structure break as a false signal without predefined criteria.
Keep exploring
These concepts are connected. Understanding one usually makes the next one easier.
The pattern of highs and lows that describes whether a market is trending or ranging.
A written set of rules defining what you trade, how you size it, and when you exit.
A predefined exit that closes a losing trade before the loss becomes serious.
The period each candle on a chart represents, from one minute to one month.
Overweighting recent outcomes when judging what is likely to happen next.