Ask anyone. They will identify the picture on the left as an atom. They might even point out the nucleus and possibly some electrons. But no matter how confident they are and how much detail they offer, they will be wrong. This is not atom.
Based on what was known about atoms in 1903, Japanese physicist Hantaro Nagaoka proposed that the structure of atoms did, in fact, resemble a solar system with particles orbiting around a central structure. It soon became evident, however, that this planetary model was impossible. Even Nagaoka disavowed his own model by 1908.
Regardless of the science, people today will still emphatically insist that the picture is, indeed, an atom. Radio has its own version of Nagaoka's atomic folly. It's called "The Rule of Three."
The Radio Rule of Three
Ask anyone how many times a commercial must be heard on the radio to be effective. They will insist the answer is 3 times. Radio account executives will tell you this. Marketing executives will tell you this. Last week I even had the owner of local carpet and flooring store tell me this. But like the people who identify the above picture as an atom, the people who abide by the "three time" rule are wrong. It is not a rule. It's not even a good idea.
This inconceivable notion of the "rule of three" is rooted in research conducted in 1890 by Herman Ebbinghaus, a German psychologist. Ebbinghuas studied how many rehearsals were necessary for his test subjects to memorize a list of nonsense syllables. Flash forward to the mid-1960s. Working from Ebbinghaus's findings, Dr. Herman Krugaman, a public opinion researcher at General Electric developed a model of effective advertising. Krugman discussed his model in an article published in Public Opinion Quarterly titled, "The Impact of Television Advertising: Learning Without Involvement."
A Myth Is As Good A Mile
In his article, Krugman explained that for a commercial to be effective it must attain three. and only three, levels of psychological exposure among the target audience. Krugman describes these three levels as "Curiosity, Recognition, and Decision." Quickly, however, Krugman's model was transmogrified by misguided marketers from three psychological exposures to three media exposures. This erroneous interpretation of Krugmen's model has survived to this day much like Nagaoka's discredited planetary atomic model.
Krugman himself was dismissive of the three exposure rule propagated by media practitioners. He said, "Let me try to explain the special qualities of one, two, and three exposures. I stop at three because as you shall see there is no such thing as a fourth exposure psychologically; rather fours, fives, etc., are repeats of the third exposure effect. He went on to say, "There is a myth in the advertising world that viewers will forget your message if you don't repeat your advertising often enough. It is this myth that supports many large advertising expenditures...I would rather say the public comes closer to forgetting nothing they have seen [or heard]. They just put it out of their minds until and unless it has some use . . . and [then] the response to the commercial continues."
One Exposure Can Be Enough
So the question remains, how many times must a radio commercial be heard before it is effective. Erwin Ephron, often considered to be the father of modern media planning, told Inside Media magazine, "Today serious students of advertising understand there is no formula answer to the effective frequency question. They believe most exposures are reminders so a single exposure, if relevant, can make the sale.”
Frequency is only one part of a successful media formula. The other components are a compelling message; a well-defined target audience; and a well-reasoned marketing objective. According to Ephron, if you deliver the right message, to the right people, for the right reason, then radio advertising can produce results with a minimum of exposures.
Read more about effective frequency in our recent article, The Radio Advertiser's Toughest Choice: Reach vs. Frequency.