Cobra Effect · Thinking and evidence
Hindsight bias
Once you know the ending, it always looks obvious.
6 cards, read aloud in 2:25, with a test and sources.
The project failed. Everyone in the room saw it coming.
The post-mortem is on Thursday. One by one, people explain that the signs were obvious. The timeline was mad. The supplier was shaky. The lead was out of her depth. Six months ago, every one of these people signed off on the plan.
1975. A young psychologist hands students a story about a war.
Baruch Fischhoff gave people a passage about a British campaign against the Gurkhas in the 1800s. It could end four ways. British win, Gurkha win, or two kinds of stalemate. Some students were told nothing. Others were told how it ended. Then everyone was asked how likely each ending had been.
Knowing the ending made it look inevitable.
Whichever ending a group was told, that group rated it as far more likely than the people who had not been told. And they were sure they would have predicted it. Fischhoff called it creeping determinism. Once you know what happened, it quietly becomes the only thing that could have.
It even rewrites your own memory.
In 1972 Fischhoff and Ruth Beyth asked students to predict what would happen on President Nixon’s trips to China and Russia. Afterwards they asked the students to recall their own predictions. People remembered giving higher odds to the things that happened. The paper is titled I knew it would happen.
That is hindsight bias, and it makes every past decision look easy.
The doctor who is sued because the diagnosis is obvious now. The analyst who is a fool for missing the crash that everyone, afterwards, saw coming. Nobody saw it coming. They saw it having come. The cruelty is that it feels like wisdom.
The only defence is a record made before the ending.
Write down what you expect, and how sure you are, before you find out. Then judge yourself against the note, not against the memory. And when you review a failure, ask how the other endings could have happened. Fischhoff found that question is one of the few things that loosens the grip.
Sources
- Hindsight bias, Wikipedia. The 1975 experiment with the four endings, the Nixon study, creeping determinism, and what has been found to reduce it. Search Fischhoff 1975 Hindsight is not equal to foresight for the paper.
- Thinking, Fast and Slow, Daniel Kahneman, 2011. Chapter nineteen, The Illusion of Understanding, is about hindsight and why it makes the past feel more predictable than it was. Kahneman was Fischhoff’s teacher.
- Baruch Fischhoff, Wikipedia. The man who ran the experiments, and the rest of his career on how people judge risk. The 1975 paper with Ruth Beyth, I knew it would happen, is listed there.
Nearby ideas
- Outcome bias. Judge a decision by what was known, not by how the dice fell.
- The narrative fallacy. We invent causes for events because stories feel like explanations.
- Confirmation bias. We look for evidence that agrees, and rarely test what could say no.
- The framing effect. The same facts, worded differently, lead to different choices.
- Loss aversion. Losing something hurts about twice as much as gaining it pleases.
- The curse of knowledge. Once you know something, you cannot see what a beginner is missing.
- Bayesian updating. Change your mind in proportion to the strength of the evidence.
- Overconfidence. Why we feel more certain than our knowledge allows.