Latest / The Copywriting Podcast with Fexingo: Sales Letters, Headlines, and Persuasive Writing / How a Single Word Made Copy 64 Percent More Persuasive
Transcript
- Lucas: So there's this classic direct-response study that keeps getting cited in copywriting circles, and for good reason. It's from the early days of mail-order advertising, and it found that swapping one word in a headline lifted response by 64 percent. Luna: 64 percent? That's massive. Which word are we talking about? Lucas: The study compared headlines that started with 'How to' versus headlines that started with 'Which.' So, 'How to repair a leaky faucet' versus 'Which faucet repair method works best?' The 'Which' version pulled 64 percent more inquiries. Luna: Interesting. So the reader is being asked to choose, not just told how. Lucas: Exactly. And it's not just about the word itself, it's about the implied promise and the mental process it triggers. 'How to' promises a process, a sequence. 'Which' promises a verdict, a comparison, a ranking. And apparently, a verdict is more compelling. Luna: That makes sense. When you're about to buy something, you want to know which option is best, not just how to do it. Lucas: Right. The copywriter behind that test, a guy named John Caples, he was a pioneer in this stuff. He wrote one of the most famous headlines in advertising history: 'They Laughed When I Sat Down at the Piano — But When I Started to Play!' That's a story headline, not a 'how to' or 'which' headline, but it follows the same principle: hook the reader with a specific, emotionally charged scenario. Luna: And Caples was all about testing everything, right? He would've loved A/B testing. Lucas: Absolutely. He said, 'Whenever you are about to write a piece of copy, put yourself in the position of the buyer. Ask yourself, What would I want to know before I buy?' And that question, 'Which,' forces the copywriter to answer that for the reader. Luna: So how can we apply this today? I mean, we're not sending out mail-order envelopes anymore. Lucas: We're not, but the principle transfers directly to subject lines, landing page headlines, even call to action buttons. Instead of 'How to save money on your electric bill,' try 'Which energy plan saves you the most?' Instead of 'How to choose a CRM,' try 'Which CRM is right for your team?' Luna: But doesn't 'which' sometimes feel a bit… clinical? Like it's a multiple-choice question? Lucas: That's the thing — it's not just 'which,' it's the whole construction. 'Which' headlines often imply a choice between a limited set of options. And when you frame it that way, you're doing two things: you're positioning yourself as the guide who can evaluate options, and you're making the reader feel like they're about to make an informed decision. That's powerful. Luna: So it's about promising a comparison. Like, 'Which of these five diets actually works?' Lucas: Exactly. And the beauty is, you don't have to be a huge brand to use it. A small e-commerce store could test 'Which winter coat is warmest?' against 'How to choose a winter coat.' The 'which' version might lift click-throughs just by framing the intent. Luna: I'm curious — is there any data on how often 'which' outperforms 'how to' in modern digital copy, or is it just that one study? Lucas: There's anecdotal evidence from several A/B tests I've seen in newsletters and landing pages. Not a huge meta-analysis, but the pattern holds: 'which' tends to work well when there's a clear decision to be made, especially if the audience is already in a research mindset. 'How to' might work better for purely educational content where someone just wants steps. Luna: So it's not a universal rule, more like a lever you can pull depending on intent. Lucas: Precisely. And that's the deeper lesson: it's not about memorizing winning words, it's about understanding what the word is doing psychologically. 'Which' invites the reader to participate in a comparison. 'How to' invites them to follow along. One is more active, the other more passive. Luna: I've seen 'Which' used a lot in quiz headlines, like 'Which Harry Potter character are you?' That's a different kind of 'which,' but it still triggers curiosity. Lucas: Right, and that's a cousin of the same principle. The quiz headline works because the reader wants to know the answer about themselves. The 'which' in our copywriting example is about the product, but it still taps into that same desire for resolution. Luna: Okay, so let's say someone is writing a subject line for a marketing email. What would you advise them to test? Lucas: I'd say, look at your current subject line and see if you can convert it into a 'which' format. So if it's 'How to improve your SEO traffic,' try 'Which SEO tactic delivers the fastest results?' That's a simple swap that could make a real difference. Luna: And what about the body copy? Does the 'which' need to carry through the whole email? Lucas: Good question. Ideally, the headline sets the expectation, and the body delivers on it. If you promise a comparison, you need to actually provide one. That's where the credibility comes in. Caples was famous for that — he always made sure the copy delivered on the promise. Luna: So the word is just the entry point. The real work is in the substance. Lucas: Exactly. And that's what separates good copy from great copy. The word gets them in, but the content keeps them. I think we often get caught up in clever phrasing and forget that the reader wants a solid answer. Luna: Before we go further, I'm curious if you've personally tested this in your own writing, Lucas. Lucas: I have, actually. I write a lot of newsletter intros, and I've tested 'How to' versus 'Which' in the opening line. The 'which' versions tend to get more replies. It's not a huge sample, but it's consistent. Luna: That's encouraging. Sometimes these classic studies feel like they belong in a museum, but the principles hold up. Lucas: They do. And that's why we keep coming back to them. There's a reason these old copywriters are still quoted — they understood human psychology better than most marketers today. Luna: Speaking of understanding human psychology, I feel like this episode has been a masterclass in that. And if you've been nodding along, thinking about how you might apply this to your own headlines or subject lines, maybe you'd consider supporting the show. We keep these conversations ad-free, and listener support is what makes that possible. If this episode has sparked something you've actually used, a small contribution at buy me a coffee dot com slash fexingo would mean a lot. Lucas: Yeah, we really appreciate that. It keeps the lights on and the coffee brewing. But back to the topic — there's another layer to this 'which' thing that I think is worth exploring. Luna: Lay it on me. Lucas: So we've talked about headlines and subject lines, but 'which' can also work in your call to action buttons. Instead of 'Learn More,' try 'Which option fits you best?' That's a bigger change, but it forces the reader to make a micro-decision right there. Luna: Hmm, that's interesting. But wouldn't that confuse people who just want to get to the next page? Lucas: It could, if the button doesn't lead to a page that actually presents options. But if you have a product lineup or a service tier, it's a great fit. The key is to make sure the next step delivers on the promise of choice. Luna: So it's not about tricking people, it's about aligning the copy with the experience. Lucas: Exactly. Copywriting is just a promise made in words. The fulfillment happens on the page. If the promise and the fulfillment don't match, you've lost trust. Luna: I think that's a great note to end on. But before we go, do you have a favorite example of a 'which' headline from the wild? Lucas: One that comes to mind is from a financial services company: 'Which retirement plan is right for you?' That's a classic. It speaks directly to a decision millions of people face, and it's much more engaging than 'How to plan for retirement.' Luna: Yeah, I can see that. It's like you're giving them a roadmap instead of a lecture. Lucas: And that's the real lesson. We're not just picking words for fun — we're choosing language that matches the way people actually think. 'Which' taps into that decision-making instinct, and that's why it works. Luna: Well, I know what I'm going to be testing in my next subject line. Thanks, Lucas. Lucas: Anytime, Luna. And thanks to everyone listening — we hope you found this useful. Until next time, keep testing.