The reason a slogan outlives the campaign

People still complete slogans for products they have never bought, from campaigns that ended before they were born. Ask the same people to recall the claim the campaign was making and most cannot. The line persisted; the argument it carried did not travel with it.

What everyone sees

A memorable slogan is credited to a clever idea, and agencies present it that way. Under that account the strongest concept should endure longest. What actually endures tends to be short, stressed and rhythmically regular, which is a property of the phrasing rather than of the thought behind it.

What is actually happening

Research on the rhyme-as-reason effect found that rhyming statements are judged more accurate than non-rhyming paraphrases with identical meaning, an effect McGlone and Tofighbakhsh attributed to processing fluency. Metrical regularity and alliteration further improve recall, as work on verbatim retention in oral tradition documents. A slogan optimised for sound is therefore easier to retrieve and feels truer, independent of what it asserts.

Why it stays hidden

The mechanism hides because form is invisible when it works. A well-made line does not feel crafted; it feels obvious, as though it were the natural way to say the thing. Attribution defaults to the idea because ideas are what people believe they remember, and the phonetic structure that carried it leaves no trace in the report.