Why mock interviews work (and why most people skip them)

There's a well-documented finding in educational psychology called the testing effect: being tested on material helps you retain it far more than re-reading that material does. It's been replicated across dozens of studies, different subjects, different populations. It's not a niche finding.

The same principle applies to interview prep. And most people's prep is almost entirely passive.

The comfortable kind of preparation

Reading a solution explanation feels productive. Watching a YouTube walkthrough feels productive. Going through a list of common questions and mentally sketching out answers definitely feels productive.

Almost none of it transfers the way you think it does.

Reading about how an algorithm works is like reading about how to drive. The knowledge is real — the explanation is correct — but you haven't practiced the thing that actually matters. Doing it under conditions that resemble the real thing.

Why people skip it anyway

Mock interviews are uncomfortable. This is true even when you're practicing alone with no one watching. There's something about pretending there's an interviewer present — committing to the performance — that creates real pressure. Most people, given the choice between comfort and practice, choose comfort and call it preparation.

There's also the embarrassment factor. Performing badly at something, even in private, feels worse than not performing at all. If you never practice out loud, you never have to confront how much harder it is than you thought. You get to keep the comfortable belief that you'd do fine if it actually counted.

This is exactly backwards. That discomfort is the signal you're doing it right.

What happens the first few times

The first time most people practice out loud, they stumble over words, forget things they definitely know, lose their train of thought mid-sentence, and feel like they know nothing. This is not a sign that they're bad at this. It's the gap revealing itself.

That gap — between knowing something and being able to perform it under pressure — is the actual thing you need to close. You can't close it by reading more solutions.

The kind of practice that actually transfers

Not all practice is equal. Solving problems on paper, or in your head, doesn't transfer as much as doing it out loud. A few specific things that move the needle:

Explain before you start. Before writing a line, say out loud what you're going to do and why. Not just the approach — the reasoning. What made you reach for this data structure. What tradeoff you're accepting.

Practice recovering, not just solving. Deliberately get it wrong sometimes. Write a solution with a bug, then find it out loud, fix it, and keep going without treating it like a catastrophe. Interviewers see this constantly and they want to know how you handle it.

Use a timer. The anxiety of watching time disappear is something you need to have felt before — not for the first time during the interview itself. Twenty minutes goes faster than you think.