Trading Psychology · Lesson 15 · Beginner
A toolkit against your psyche
You build yourself a mechanical rule set from a checklist, a pre-mortem and a journal that decouples action from feeling.
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External alarms
System 1 sends no warning signal when it becomes unreliable. Skill intuition and heuristic hallucination feel identically certain, which is why you need external tools.
Checklist and pre-mortem
A simple pre-trade checklist beats gut feeling and forces the switch to System 2. The pre-mortem assumes the trade is already at maximum loss and asks why. That bypasses WYSIATI and confirmation bias.
Build your mechanical rule set and tick off every point.
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The key points at a glance
- System 1 sends no warning signal when it becomes unreliable.
- A pre-trade checklist and a pre-mortem force System 2.
- Defaults beat willpower.
Deep dive
Why do you need external alarms instead of gut feeling?
Kahneman sums it up in one sentence: 'We would all like to have a warning bell, but no such bell is available.' Genuine skill and pure hallucination feel identically certain from the inside, so you have to install external alarms.
On top of that, trading is a wicked environment: the feedback is delayed and misleading. A trade that breaks the rules sometimes wins on luck, a clean one loses on bad luck. So without tools you learn the wrong lessons.
How to build a checklist and a pre-mortem properly
An equally weighted checklist of five to 6 points beats gut feeling, as shown by the Apgar score, Meehl and Dawes. Score each point individually, otherwise the halo effect colors everything green.
- Setup valid, stop defined, invalidation clear
- Position size derived from the risk, risk-reward above your target value
- Base rate of the setup from your own journal
- Broken-leg rule: only override on rare AND decisive information
- Pre-mortem: 'the trade is at maximum loss, why?' lists your sources of error
Journal, vocabulary, and why defaults beat willpower
The decision journal separates process from outcome: first note the reason, the invalidation and the risk, then look at how it turned out. Label every bad trade with the correct name, like loss aversion or sunk cost.
Kahneman uses organ donation rates to show how brutally defaults work: around 100 percent consent under opt-out, only 4 percent under opt-in. Lock in important decisions while System 2 is fresh, then let the mechanics do the work.
Sources: Kahneman, Douglas, Elder, Schwager, Taleb
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