Analysing your IQ
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AKA: "Optimistic Scheduling"
The tendency to underestimate how long tasks will take, even when you have past evidence.
Planning Fallacy is one of the most common cognitive errors—and one of the hardest to spot in yourself. This page explains what it is, why your brain does it, and how to mitigate it.
You assume “this time” a project will take two days—then it takes two weeks, again.
This bias is particularly dangerous because it operates below conscious awareness. By the time you notice it, the damage is often done.
This error is driven by Inside view focus: you imagine the ideal path and ignore friction, delays, and coordination costs..
The mechanism is rooted in inside view focus: you imagine the ideal path and ignore friction, delays, and coordination costs.. Your brain isn't broken—it's running outdated software in a new environment.
In investing: Planning Fallacy leads to holding losing positions too long or selling winners too early.
In relationships: This bias causes people to interpret ambiguous signals in ways that confirm existing beliefs about partners.
In work: Planning Fallacy makes it harder to update strategies when market conditions change.
In health: People ignore symptoms that contradict their self-image as "healthy" or "young."
Planning Fallacy has been studied extensively since the cognitive revolution. Research consistently shows that even warned subjects fall for it—awareness alone doesn't provide immunity.
Use reference class forecasting: base your estimate on similar past tasks. Add a buffer for interruptions.
Seek disconfirming evidence: Actively look for data that challenges your current belief.
Use decision journals: Write down predictions before outcomes are known, then review accuracy.
Consult diverse perspectives: People with different backgrounds spot different biases.
Implement decision rules: Pre-commit to criteria before emotionally charged situations arise.
Time-box decisions: Revisit important conclusions after a cooling-off period.
Some brains are more susceptible to this than others. Test your Discipline to find out.
The tendency to underestimate how long tasks will take, even when you have past evidence.
The alternate name "Optimistic Scheduling" captures the intuitive essence of the bias. Planning Fallacy is the formal psychological term, while "Optimistic Scheduling" describes what it feels like in practice.
Use reference class forecasting: base your estimate on similar past tasks. Add a buffer for interruptions.
The underlying mechanism is inside view focus: you imagine the ideal path and ignore friction, delays, and coordination costs.. Human brains evolved heuristics for speed and survival, not accuracy in modern contexts.
Yes. Intelligence doesn't provide immunity—sometimes it makes the bias worse because smart people are better at rationalizing. Awareness and structured decision processes are more protective than raw IQ.
You assume “this time” a project will take two days—then it takes two weeks, again.