Once you know something well, you can’t imagine not knowing it — so you skip steps, use jargon, and explain over people’s heads without realizing. It’s why experts are often the worst teachers, and clear communication is so rare.
The curse of knowledge: once you know something, it becomes nearly impossible to imagine what it’s like not to know it — so you communicate as if your audience already shares your knowledge.
In a classic experiment, ‘tappers’ tapped out the rhythm of a famous song on a table and guessed how often ‘listeners’ would name it. Tappers predicted 50%; listeners got it about 2.5% of the time. In the tapper’s head the song plays in full; the listener hears only disconnected knocks. That gap is the curse of knowledge, named by Chip and Dan Heath: the song in your head makes it impossible to hear the bare taps the way your audience does.
It’s why the brilliant professor loses the class, the engineer’s docs are unreadable, and your perfectly clear instructions confuse everyone. Knowledge isn’t just added to your mind — it rewires it, so the steps you’ve automated become invisible to you. You can’t un-know the jargon, the context, the leaps that are now obvious. And the more expert you are, the worse the curse, which is why deep experts are so often the poorest explainers.
You can’t lift the curse, but you can route around it. Test on a real novice and watch where they get lost (you can’t predict it from inside). Strip jargon and spell out the steps you’d be tempted to skip. Use concrete examples instead of abstractions — they survive the gap. And remember the tappers: what’s a full song to you is just taps to them, so over-explain the thing you’re sure is obvious.
It’s why most explanations, docs, and pitches fail — the better you know something, the less you can feel what a beginner doesn’t. Clarity takes deliberate work, not just expertise.
It’s not ‘dumb everything down’ or ‘expertise makes you a bad communicator forever.’ The fix isn’t less knowledge — it’s deliberately rebuilding the path for someone who lacks it. Experts can explain beautifully; they just have to test against a real beginner instead of trusting their own sense of what’s clear.
Try to answer in your head first — that effort is what builds the memory.
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