This is a Lexicon entry: the mechanism, when it shows up, and the countermeasure. The full correction, with real-world cases and the audit prompt, hasn't been written yet.
Definition
Primary concept: Cognitive Dissonance. Choice-Supportive Bias is Cognitive Dissonance resolved by retroactively improving the chosen option.
When it shows up
After committing to a significant choice: career path, purchase, relationship. In the days and months following the decision.
Failure mode
Memory of the chosen option improves; memory of the rejected option degrades. The mind constructs post-hoc justification of the choice and calibrates remembered features to support it. The choice feels retrospectively obvious even if it was a coin flip.
Countermeasure
Keep a decision journal written at the time of the choice. Record your uncertainty and reasoning. Revisit when evaluating whether the decision was good; memory will have moved without the journal.
Related concepts
Also connected in the mapThe Sunk Cost Fallacy·Cognitive Dissonance·Commitment Bias·The Endowment Effect
Origin
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Entry #90 of 631 in The Lexicon · see the full Lexicon