Ask the same question twice, and watch what happens between the two answers. That's where most people give themselves away. 

A candidate who says they led the migration to a new system at their last job should describe the same problem and solution in detail during the second interview. A first date who mentions a recent trip, a new car, or a bonus should hold up the same way when a casual follow-up comes later in the night.

Those padding the truth may add details that weren't there before or back off parts of their original story that don’t hold up. That's the utility of a good follow-up: it works like an invitation when you’re dealing with incomplete information. 

1. Act Like You Know More Than You Do

At the poker table there’s a word for the flicker that gives someone away: a tell. It's rarely the big stuff like a visible wince or cracking voice. The real tells are small: a half-second pause before an answer, shifting details, or an ever-expanding explanation. 

Researcher Cody Porter built a technique around making a tell show up on command. It's called asymmetric information management, and the mechanics are almost sneakily simple: pretend you have information, and watch how someone's story shifts to match it. Mention that you've seen the invoice, heard from the other side, or compared notes with someone else in the room, whether or not any of that happened. Someone telling the truth has nothing to bend around, so the story holds. If they’re managing a version of events, they’re likely to work backward, trying to guess how much you know and letting it shape what they say next.‍

2. Ask the Right Question in the Right Way

Detective Joshua Mason built his method on one small swap: trade "why" for "what." As he tells Fast Company, questions like "What happened next?" or "What did you do when that happened?" push someone to produce a new piece of the story on the spot, something they haven't rehearsed. A prepared reason is easy to repeat word for word, but details fabricated under pressure rarely survive a second telling.

Say a vendor's quote comes back $3,000 higher than the one from three months ago, pinned on rising material costs. Ask what's driving the number: "What exactly changed in your costs since the last quote?" A legitimate increase breaks down the same way every time, materials here, labor there. But start noticing moving pieces on the second pass and there’s more to unpack. 

None of this needs to use the tone of an interrogation. The best version sounds like idle curiosity, which is exactly why nobody sees it coming.‍

3. Let the Silence Do the Work

Asking the question is the easy part. What happens in the ten seconds after is the real tell. Instead of rushing to fill a pause, offer a way out, or apologize for pushing, let them carry the weight of their words. 

Notice if they offer a correction to their story or add a detail without being prompted. These are the moments a story confirms itself or starts coming apart in real time. None of those reactions prove anything in isolation, but strung together over a few questions, they add up to a sharper sense of what's true. Let it happen in the open. The urge to jump in and smooth it over is worth resisting when you’re after the truth. 

Back to You 

Deception collapses under its own weight — it just needs a little room to fall apart. Feign a bit of context you don’t have, trade ‘why’ for ‘what,’ and let silence handle whatever’s left over.

The next time a claim or story feels slightly off, step back and let the truth introduce itself.