In mid-1978 a rumour started in the American south initially aimed at Wendy’s, and later at McDonalds, that their meat patties contained earthworm fillers.
This was totally false but when picked up by a so-called reputable press, many people believe what they read especially if it is simple to understand and could be credible – that is, it sounds like it could be correct. Apparently, the story appeared in a local paper (source unknown) and was then picked up by a local current affairs TV station.
Wendys was phoned by someone who thought they heard about it on 20/20 or perhaps 60 minutes which was incorrect but now all of a sudden the rumour gained more unfounded credibility and momentum. When people pass on what they “hear” they inevitably get it wrong or embellish it to make it an even more interesting and newsworthy story.
Before long people were wondering if it really was true and many were not willing to take the “risk” of eating hamburgers which resulted in one McDonalds store seeing its sales drop by 30%. Clearly, this needed to be nipped in the bud before it got out of hand.
The PR people immediately got onto it at McDonalds and released information that proved its burgers were made with “Nothing but 100% pure United States Government-inspected ground beef.”
Ultimately the rumour was quashed following a national campaign that promoted the purity of its ingredients but Ray Kroc – the founder of the modern McDonalds – brilliantly added a truly credible reason why the rumour was false when he announced “We couldn’t afford to grind worms into our meat because hamburger costs a dollar and a half a pound, and night crawlers six dollars” and as suggested by Chip and Dan Heath in their book Made to Stick (p282) Kroc could have finished by saying “if someone ever tries to sell you a WormBurger, you should worry about them secretly filling it with beef.”
The take-away from this story is that credibility determines whether an idea will stick in peoples’ minds or not. And it follows that credibility is the only way to change peoples’ minds. There MUST be a reason to believe. In fact as the Heath brothers explain in their book, for an idea to stick (or be unstuck) it needs to be simple (easy to understand AND recall e.g. Heath’s humorous suggestion about wormburgers being secretly filled with beef – that’s remarkable in Seth Godin’s words! ), unexpected or paradoxical (this is what gets remembered and remarked on), concrete (can be envisioned), credible (makes intuitive sense), emotionally connectable (can be felt), and wrapped in a story (give it context.) This framework can be summarised with the acronym SUCCESS.