Hindsight Bias

The college entrance exam results come out, and your math score is disappointing. A relative says, "I could tell you hadn't studied enough math." Yet before the exam, the same person said, "Math should be fine."

This is hindsight bias: once we know the outcome, we feel it was predictable all along, and we quietly rewrite what we believed beforehand.

Why it's dangerous

• Memory gets rewritten: you genuinely believe you saw it coming. You're not lying.
• Predictability gets overrated: in hindsight, every clue points to the outcome; beforehand, the clues were usually mixed and contradictory.
• You stop learning: if you think "I knew it," you won't reflect on what you got wrong. Or you beat yourself up for missing something "so obvious" that wasn't obvious at the time.

After a stock-market crash, your feed fills with analyses of "the warning signs." But if it had been that obvious, plenty of people would have gotten out beforehand.

This is exactly why FoMind exists

Writing down your forecast and reasoning before the outcome is known is the most effective defense against hindsight bias. A probability and reasoning in black and white don't change with the result.

How to guard against it when forecasting

• Make your probability and reasons specific: not just "probably," but "65%" with concrete reasons.
• Write down what information would change your mind, so you can compare later.

How to spot it in a review

• Read what you wrote at the time before judging yourself; don't rely on memory.
• Ask: "Given what I knew then, what probability was reasonable?" rather than "What does it look like it should have been now?"
• If your first reaction in a review is "That was so obvious, I should have seen it," pause: was it really obvious then? Did you actually have those clues that now look so clear?