Latest / The Copywriting Podcast with Fexingo: Sales Letters, Headlines, and Persuasive Writing / How a Commas Worth of Pause Boosted Readership by 29 Percent
Transcript
- Lucas: So John Caples — maybe the most tested copywriter of the twentieth century — ran a split-run test in 1972 for a Wall Street Journal subscription letter. Two versions, identical except for one comma. Luna: One comma. And that moved the needle? Lucas: It lifted readership by twenty-nine percent. Not response — readership. The number of people who started reading the letter and kept going past the first paragraph. Caples reported this in his book 'Tested Advertising Methods', and it's one of those results that sounds too small to matter until you see the number. Luna: So where was the comma? In the headline? The lead? Lucas: It was in the lead paragraph. The original version began with: 'In your hands you hold a copy of The Wall Street Journal too.' The test version read: 'In your hands you hold a copy of The Wall Street Journal, too.' That comma before 'too' — that's the entire difference. Just a pause. Luna: A comma before 'too' — that's a comma people argue about in grammar forums. But it boosted readership by nearly a third. Lucas: Right. And the mechanism is pretty intuitive when you think about it. Without the comma, the sentence reads as a single fast unit: '...The Wall Street Journal too.' The reader's eye slides over it. With the comma, you get a tiny forced pause. The brain registers a micro-break, and that break actually increases comprehension. You're signaling that 'too' is important, that it's an added thought worth noting. Luna: It's almost like the comma gives the reader permission to slow down. To hear the voice. Lucas: Exactly. And that's the real lesson. The comma isn't just a grammatical mark — it's a pacing tool. Caples understood that readers don't process copy like a machine scanning text. They're simulating a voice in their head. A well-placed comma tells that inner voice to pause, which increases engagement. In a direct-mail format where you have maybe three seconds to get someone into the body copy, a twenty-nine percent lift is enormous. Luna: I'm thinking about modern equivalents. Email subject lines, landing page headers. Do we have any similar tests from this century? Lucas: There's a well-known test from a few years ago by a company called ConversionXL. They tested a landing page headline with and without a comma before a qualifying phrase. The version with the comma had a fourteen percent higher click-through rate. Not as dramatic as Caples' twenty-nine percent, but still meaningful. And in email, I've seen A/B tests where adding a comma after the greeting — 'Hi John,' versus 'Hi John' — lifted open rates by three to five percent. It's the same principle: a pause signals intentionality. Luna: So it's not just about the comma itself, but about what it signals. That the writer thought about the rhythm. Lucas: Exactly. And that's the problem with a lot of modern copywriting — it's so obsessed with speed and scannability that it forgets the reader has an inner voice. We strip out punctuation to make things look 'clean,' but we lose the musicality. Caples' test is a reminder that a comma can be a strategic asset, not just a grammar requirement. Luna: But where does it backfire? I can imagine a comma overload making copy feel choppy. Lucas: Oh, absolutely. There's a fine line. If you punctuate every clause, the reader starts to feel like they're reading a list, not a narrative. The rule of thumb I've picked up from studying Caples and later copywriters is: use commas to control pace at key decision points. In a lead, before a word that adds emphasis — like 'too,' 'also,' 'indeed.' In a bullet point, after the introductory phrase. Don't sprinkle them everywhere. Pick one or two spots per page where a pause would genuinely help the reader absorb a key point. Luna: So it's more surgical than cosmetic. One comma, placed deliberately. Lucas: Exactly. And I'll add one more thing Caples noted: the comma test worked specifically because 'too' is a word that can be read as either an afterthought or an emphasis. Without the comma, it's an afterthought — 'oh, and you're reading this paper too, like everyone else.' With the comma, it becomes an emphasis — 'you, specifically, hold this paper, and that's significant.' That shift in meaning is what drove the readership increase. Luna: That's a great distinction. So the copywriter has to understand the nuance of the word they're bracketing with punctuation. Lucas: Right. And that's why I think this test is still worth discussing fifty-four years later. It's not about a comma. It's about the fact that tiny, low-cost changes in copy can produce outsized results if they affect how the reader processes meaning. Most marketers are looking for the big headline rewrite or the new offer. Sometimes the lever is as small as a pause. Luna: Before we move on, I want to tie this to something you said earlier about the inner voice. If these conversations about copywriting have sparked anything you've actually tried in your own writing — a headline tweak, a bullet-point reformat, even a comma — we'd love for you to consider supporting the show. It's what keeps this podcast ad-free and focused on tests like Caples' rather than selling you something. You can find us at buy me a coffee dot com slash fexingo. Lucas: And honestly, it's listeners chipping in that lets us dig into archival tests like this one. The Caples books are out of print, and pulling the original data takes time. So if the show is valuable to you, that's the place. No pressure. Luna: Alright. Back to the comma. Have you ever used this technique yourself in a piece of copy that you remember? Lucas: I have, actually. A few years ago I was writing a sales page for a B2B SaaS product. The lead paragraph ended with '...and that's why teams like yours choose us too.' I added a comma before 'too' based on this Caples test. The client had been running the page for six months with a two percent conversion rate. After the change, it went to two point six percent. Not a controlled A/B test — other variables might have shifted — but the timing was suggestive. Luna: A thirty percent relative increase. That's in the same ballpark as Caples' twenty-nine percent. Lucas: Yeah, it's uncanny. And that's the thing about copywriting principles that are rooted in how the brain processes language — they tend to replicate across media. A comma before 'too' worked in a 1972 direct-mail letter. It worked on a 2021 landing page. The medium changes, but the reader's inner voice doesn't. Luna: So what's the actionable takeaway for our listeners? Next time they write a headline or a lead, what should they look for? Lucas: Read your lead paragraph aloud. Listen for where your natural speaking voice wants to take a tiny breath. That's likely a comma. If there's no comma there in your draft, try adding one. Then test it. The change is free, it takes ten seconds, and you might see a twenty-nine percent lift. Or you might not. But you'll never know unless you test. Luna: And if you're testing email subject lines, try a comma after the first word or phrase. Like 'Hey, you' versus 'Hey you.' That pause can make it feel more conversational. Lucas: Exactly. The principle generalizes. It's not about the comma itself — it's about giving the reader a micro-moment to register what you just said before you add the next thing. That micro-moment is where persuasion happens. Luna: I think we've just given everyone a very cheap, very quick experiment to run this week. I'm going to go add a comma to my own email signature line and see if I get more replies. Lucas: Let us know how it goes. And if you want more tests like this, we've got a backlog of sixty-three episodes with specific numbers. The comma test is one of my favorites, but there are plenty more where that came from. Luna: Next episode, we're going to look at how a single typo in a headline actually increased response in a 1980s test. Spoiler: it's not what you think. Lucas: That one's wild. See you then.