The curse of knowledge

A doctoral student ran a simple experiment that revealed something uncomfortable about experts. She had people tap out the rhythm of a famous, instantly recognisable song, just the taps, on a table. Then she asked the tappers to predict how often a listener would name the tune. The tappers guessed about 50 percent. The real number was 2.5 percent. In their own heads, the tappers could hear the whole song, melody, words, arrangement, playing loud and clear, so it seemed obvious. The listeners heard only disconnected knocks on a table. The tappers could not un-hear the music, and so they could not imagine the listener's blankness. This is the curse of knowledge: once you know something, you lose the ability to imagine not knowing it.

Once you understand something well, you cannot easily feel what it is like to not understand it, and that gap makes experts terrible at judging what is hard for a beginner. It is why the specialist's explanation loses the room, why the veteran underestimates how long a newcomer needs, why obvious to you is baffling to someone else. When you teach, brief, or hand off work, assume the other person hears knocking, not music, and spell out what feels too basic to mention, because the thing you find too obvious to say is often the exact thing they are missing. Some of what an expert knows cannot be put into words at all, which is tacit knowledge.

Source: Camerer, Loewenstein and Weber, The Curse of Knowledge in Economic Settings, Journal of Political Economy, 1989, which named the effect. The tapping study is Elizabeth Newton's 1990 Stanford dissertation, unpublished. Popularised in Heath and Heath, Made to Stick, 2007.

Made to Stick

Chip and Dan Heath, 2007

Why some ideas land and others die, and how expertise quietly gets in the way of being understood.