Why Does Explaining Reveal That We Do Not Really Understand?

We use a flushing toilet every day and may naturally assume that we know how it works. Yet if asked to begin with pressing the button and explain, step by step, how the cistern, valves, water level and siphon interact, the account often breaks down after only a few links. Knowledge has not suddenly disappeared; familiarity was being mistaken for an understanding of the mechanism.

Rozenblit and Keil called this tendency the illusion of explanatory depth. Participants first rated their understanding of everyday devices and natural phenomena, then wrote detailed explanations and rated themselves again. Ratings generally fell after the attempt. The miscalibration was stronger for explanatory knowledge involving complex causal relations than for factual, procedural or narrative knowledge.

One source of the illusion may be that knowledge is distributed across our surroundings and other people. We recognise parts, know what an object does and trust that details can be found when needed, so the whole causal chain feels as though it already exists in our own minds. Fluent terminology can strengthen that feeling. But knowing what something does, recognising it and being able to explain why each step occurs are different abilities.

This does not mean that every halting explanation proves total ignorance. Verbal skill, the wording of the task, complexity and prior expertise all affect performance, and one experiment cannot diagnose an individual. A better self-check than asking “Do I understand?” is to draw the process or explain it to someone, pausing at each “and then” to ask what makes the next event occur. Explanation is valuable not only for displaying knowledge but also for locating precisely where it ends.

https://pmc.ncbi.nlm.nih.gov/articles/PMC3062901/
https://doi.org/10.1207/S15516709COG2605_1