Biases in thinking
Curse of knowledge
Once you know something, it's hard to imagine not knowing it, so experts explain things in ways beginners can't follow.
Experts skip steps, use jargon and assume context without noticing. To them it's all obvious; to a newcomer it's a wall.
Write for someone new, test instructions with people who haven't seen the product, and watch where they get stuck.
In practice
Help pages written by the engineers who built a feature that describe it in terms of its settings instead of the problem it solves.
Common mistake
Testing a flow only with the team that designed it. They can't un-know what they know.
Where it comes from
Named by economists Colin Camerer, George Loewenstein and Martin Weber in 1989. In Elizabeth Newton's 1990 study, people tapping out songs expected listeners to guess half of them; listeners got about one in forty.