isolation is powerful but misleading. For a start, while humans have accumulated a vast store of collective knowledge, each of us alone knows surprisingly little, certainly less than we imagine. In 2002, the psychologists Frank Keil and Leonid Rozenblit asked people to rate their own understanding of how zips work. The respondents answered confidently — after all, they used zips all the time. But when asked to explain how a zip works, they failed dismally. Similar results were found when people were asked to describe climate change and the economy. We know a lot less than we think we do about the world around us. Cognitive scientists call this ‘the illusion of explanatory depth’, or just ‘the knowledge illusion’.
How does a zipper work? Rate your understanding on a scale from 0 (no clue) to 10 (easy-peasy). Write the number down. Now sketch out on a piece of paper how a zipper actually works. Add a brief description, as through you were trying to explain it very precisely to someone who’d never seen a zipper before. Give yourself a couple of minutes. Finished? Now reassess your understanding of zippers on the same scale.
Leonid Rozenblit and Frank Keil, researchers at Yale University confronted hundreds of people with equally simple questions. How does a toilet work? How does a battery work? The results are always the same: we think we understand these things reasonably well until we’re force to explain them. Only then do we appreciate how many gaps there are in our knowledge You’re probably similar. You were convinced you understood more than you actually did. That’s the knowledge illusion.