Illusion of Explanatory Depth
People think they understand how a feature works — until you ask them to walk through it step by step, and their mental model falls apart.
Why PMs should care
Stakeholders — and, embarrassingly, PMs themselves — often believe they understand how a feature works until someone asks them to explain it step by step.
The feeling of understanding is cheap. Actual understanding requires walking through each screen, each error, each edge case.
PMs can use this carefully in meetings, and should. Asking 'walk me through exactly what the user sees when they click this button' collapses a lot of 'I know how this should work' objections into 'actually, I don't'.
Tone matters. Done aggressively, this feels patronising and creates enemies. Done as a genuine attempt to get everyone aligned on the current state before the debate, it's one of the most useful tools for rescuing a meeting that's about to make a decision based on three different mental models of how the feature works today.
Example in product work
An exec objects to the proposed changes to the deposit flow: 'I don't see why we need to change it — the current flow is fine.'
The PM says, 'before we debate the changes, can you walk me through what you think the user sees today, from the home screen to the deposit being confirmed?'
The exec starts describing the flow. At step three, they pause: 'wait, do we show the settlement time before or after they confirm?' A few seconds later: 'actually, I'm not sure we show it at all — do we?'
By the end of the walk-through, the exec has realised their mental model was of a flow from two redesigns ago. The objection dissolves without anyone having to win an argument. Everyone leaves the meeting aligned on what the product actually is — which is usually more than half the battle.
What to do when you see it
- Feeling like you understand something is cheap. Actually understanding it requires walking through every screen, every error, every edge case.
- 'Walk me through exactly what the user sees when they click this' collapses a lot of 'I know how this should work' objections into 'actually, I don't'.
- Done aggressively, this is patronising and creates enemies. Done as a genuine request to align, it saves the meeting.
- It's one of the most useful moves for a meeting where people are debating based on three different mental models of how the feature currently works.
Sources & further reading
- The misunderstood limits of folk science — Rozenblit & Keil, 2002The original Cognitive Science paper that coined the term and demonstrated the effect experimentally.
- The Illusion of Explanatory Depth — Scientific AmericanAn interview with Steven Sloman covering the Rozenblit & Keil research and its implications for decision-making and communication.