Did Pepsodent Teach America to Brush? Duhigg vs Hopkins's Own Words

Charles Duhigg’s The Power of Habit (2012) says Claude Hopkins made Americans brush their teeth by selling a cue, the film on your teeth, and a reward, the tingle of mint and citric acid. Checked against Hopkins’s own 1927 memoir, the film part holds up, the tingle part is nowhere in his account, and Hopkins himself wrote that advertisers cannot profitably change habits. The tidy loop is Duhigg’s reading, not Hopkins’s.

What does Duhigg’s Pepsodent story actually claim?

In the excerpt Slate published in 2012, Duhigg writes that “Before Pepsodent, almost no Americans brushed their teeth.” He reports that a decade after Hopkins’s campaigns, pollsters found toothbrushing had become a daily ritual for more than half the population. The ad line he quotes is the famous one: “You’ll feel a film.” He then says Pepsodent contained citric acid and mint oil, irritants that create a tingling sensation, that customers came to expect and miss the tingle, and that once people equated it with clean, brushing became a habit. A brand manager he quotes says the tingling does not make the toothpaste work better.

Blog summaries also cite “7 percent to 65 percent”; that figure was not in the Slate excerpt, so treat it as unsourced.

What did Hopkins say drove it?

I read the Pepsodent chapter of My Life in Advertising (Harper & Brothers, 1927) on the Internet Archive. His account has four moving parts.

First, the film. Reading “dry” dental books, he found “a reference to the mucin plaques on teeth, which I afterward called the film.” Duhigg has this right.

Second, the appeal. He decided to sell Pepsodent “as a creator of beauty” and rejected prevention and scare tactics, because people “will do anything to cure a trouble, but little to prevent it.” Every illustration showed attractive people with good teeth.

Third, the offer. Asking for a purchase met apathy, so ads offered a free sample and never mentioned price. Featuring “free” at the top of the ad “divided our results by four” for hygiene products.

Fourth, measurement. Every ad was keyed by coupon, and he learned his mistakes “in a week.” He credits the result to “countless tests” that taught him “the right human psychology.”

Claim	Duhigg (Slate excerpt)	Hopkins (1927 memoir)
Tooth film as the hook	Yes	Yes, from a dental text
Citric acid and mint tingle as reward	Yes	Not mentioned in the chapter
Beauty as the appeal	Minor	Chief appeal
Free samples and coupon testing	Not in the excerpt	Central
Advertisers can change habits	Implied yes	“No one can profitably change habits in paid print”

That last line is in a different chapter, in a passage about the cost of converting non-users: he figured converting people to the toothbrush to win new paste users could never pay back, because “new habits are created by general education.” Hopkins’s picture is of an advertiser arriving after the habit exists. My reading, not his words: Pepsodent was selling to people who already had some reason to brush.

Is there a historians’ rebuttal?

I looked for one and did not find a dedicated write-up of Duhigg’s Pepsodent chapter, so I will not invent one. What I can say is narrower. The Pepsodent chapter of Hopkins’s memoir does not name any survey of brushing rates and does not claim to have created the practice. It claims Pepsodent was “the star dentifrice success” in “a few short years” and sold in 52 countries by the time of writing. How much of any rise in brushing was Pepsodent is a question the memoir cannot settle, because its author was reporting his own results.

What does habit research say about cue-reward loops?

Wendy Wood and David Neal’s 2007 paper in Psychological Review (volume 114, pages 843-863) is the standard modern statement. Their model says habits emerge “from the gradual learning of associations between responses and the features of performance contexts” such as physical settings and preceding actions. Rewards have a role in that learning: they describe how reward value gets attached to context cues so the cues come to motivate. But once a habit is practiced, rats stop adjusting to a devalued food pellet, which suggests performance depends on the context, not the prize.

That fits the field data in Wood, Quinn and Kashy’s diary study, where habits lived in places. It also fits Verplanken’s work on habits after a move. A tingle may have helped some people repeat brushing, but nothing in this research says a sensation is the active ingredient, and Duhigg’s own brand-manager quote says the sensation is cosmetic.

How does this connect to the Atomic Habits version?

James Clear’s article “The Three Steps of Habit Change” says habit building “can be divided into four simple steps: cue, craving, response, and reward.” A footnote there says readers of Duhigg “will recognize these terms” and that he means to pick up where Duhigg left off. I checked Clear’s website text only, not the book.

Clear’s craving step is the sensible repair of Duhigg’s chapter: the tingle story is really a claim about wanting. The problem is that the Pepsodent evidence for craving is a brand-manager anecdote, not a measurement. The other gap is the one Wood and Neal point at: a loop with a reward in it can describe how a habit is learned, while the context does the work afterward. Clear’s Vietnam heroin example leans on exactly that context logic, and it has its own complications.

Why does the Hopkins method still matter?

The part of Hopkins that survives the check is the measuring. He kept coupons keyed to headlines and killed what failed within a week. That test-and-revise habit sits close to Frank Gilbreth’s motion studies: watch what people do, then change the sequence. For a morning habit the inference, which no study here tested, is that a deadline tied to a place beats a reward you hope to crave. DontSnooze applies a deadline of that kind: when the alarm fires you have 30 seconds to record a video showing you are up, and if you miss it a random photo from your camera roll goes to friends you chose.

Still unverified: Duhigg’s brushing percentages and what Pepsodent’s formula contained. The Wikipedia entry I opened lists pepsin and a sassafras flavor, not citric acid.

Questions about the Pepsodent habit story

Did Pepsodent really make Americans start brushing their teeth?

Not on the evidence Hopkins left. His memoir says Pepsodent built nationwide demand in one year and worldwide demand in four, but it also says no advertiser can profitably change habits in paid print, and that the advertiser arrives after general education has changed them. Duhigg’s claim that almost no one brushed before Pepsodent is his own; I found no historian’s study in this session that tests it.

Is the tingle from citric acid and mint oil in Hopkins’s writing?

No. The tingle, the citric acid and the mint oil come from Duhigg’s chapter, where a brand manager says the tingling does not make the toothpaste work better. In the full text of My Life in Advertising, my text search of the Pepsodent chapter found no mention of a tingle, citric acid or mint. Hopkins describes a beauty appeal, a film, free samples and keyed coupons.

Do habits form from a cue and a reward, or from repeating things in the same place?

Both appear in the research, with different weight. Wood and Neal’s 2007 model says habits come from slowly learned links between a response and the context it usually occurs in, and that rewards help in learning by attaching motivation to the cues. Once a habit is established, performance in animal studies stops tracking how much the reward is worth, which puts the weight on context.