Hindsight in the Valley of the Normal

From Nobel-laureate Daniel Kahneman’s Noise: A Flaw in Human Judgement:

More broadly, our sense of understanding the world depends on our extraordinary ability to construct narratives that explain the events we observe. The search for causes is almost always successful because causes can be drawn from an unlimited reservoir of facts and beliefs about the world.


This continuous causal interpretation of reality is how we “understand” the world. Our sense of understanding life as it unfolds consists of the steady flow of hindsight in the valley of the normal. This sense is fundamentally causal: new events, once known, eliminate alternatives, and the narrative leaves little room for uncertainty. As we know from classic research on hindsight, even when subjective uncertainty does exist for a while, memories of it are largely erased when the uncertainty is resolved.

Noise is a good book. It’s not an exciting book–though neither is Thinking, Fast and Slow for that matter–but it’s an important book. Bias is important, but human noisiness and our imperfect and very noisy systems are also important: Judgments (predictions, decisions) are hard to get right, and so much of the world’s punditry is just storytelling.

Doctors make dozens if not hundreds of little and big decisions every day. And I know that not only I am noisy, but I’m noisy in a variety of ways. A big part of my deliberate practice as it pertains to radiology is to try to limit how much noise distorts my decision-making and the quality of my reports.

We want to be not just good but consistently so.


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