Take the tap test before you present

Literally tap out a melody and notice how obvious it is to you — but invisible to listeners.

Why it works

The tap test (from Elizabeth Newton’s 1990 dissertation, popularized by the Heaths) makes the curse of knowledge visceral: tappers who know the song predict 50 % of listeners will recognize it; actual recognition is roughly 2.5 %. The experience forces an expert to feel the gap between their internal signal and what others receive. That felt gap is the calibration data experts normally lack.

How to do it

1. Tap out a well-known song on a table and ask a colleague to name it.
2. Before you reveal the song, guess what fraction of people will get it right.
3. Compare your guess to the actual result — the ratio is your personal curse-of-knowledge index.
4. Apply the same calibration question before any explanation: "What fraction of my audience has never heard this?"

Evidence

Newton (1990) showed tappers predicted ~50% recognition; actual rate was ~2.5%, a large and consistent gap. The Heaths used it as the anchor example for the curse of knowledge in Made to Stick. (observational)

This is a single lab paradigm, not a systematic review; it illustrates rather than quantifies the effect in real-world teaching settings.

Sources

• Newton, E. (1990), The Rocky Road from Actions to Intentions (Stanford dissertation)

Common mistake

Using the tap test once as a party trick rather than as a recurring calibration practice before any high-stakes explanation.