The subject on effective frequency is quite controversial. Many people have their own definition on what this word means. There are also numerous studies with their own theories or models as to what the correct number is for effective frequency.
There are several definitions of effective frequency. The following are some key examples:
He discovered that distributing learning trials over time is more effective in memorizing nonsense syllables than massing practice into a single session; and he noted that continuing to practice material after the learning criterion has been reached enhances retention.
Using one of his methods called savings as an index, he showed that the most commonly accepted law of association, viz., association by contiguity (the idea that items next to one another are associated) had to be modified to include remote associations (associations between items that are not next to one another in a list).
He was the first to describe primacy and recency effects (the fact that early and late items in a list are more likely to be recalled than middle items), and to report that even a small amount of initial practice, far below that required for retention, can lead to savings at relearning.
He even addressed the question of memorization of meaningful material and estimated that learning such material takes only about one tenth of the effort required to learn comparable nonsense material.
This learning curve research has been used to help researches study advertising message retention.
Thomas Smith wrote a guide called Successful Advertising in 1885. The saying he used is still being used today.
The first time people look at any given ad, they don't even see it.
The second time, they don't notice it.
The third time, they are aware that it is there.
The fourth time, they have a fleeting sense that they've seen it somewhere before.
The fifth time, they actually read the ad.
The sixth time they thumb their nose at it.
The seventh time, they start to get a little irritated with it.
The eighth time, they start to think, "Here's that confounded ad again."
The ninth time, they start to wonder if they're missing out on something.
The tenth time, they ask their friends and neighbors if they've tried it.
The eleventh time, they wonder how the company is paying for all these ads.
The twelfth time, they start to think that it must be a good product.
The thirteenth time, they start to feel the product has value.
The fourteenth time, they start to remember wanting a product exactly like this for a long time.
The fifteenth time, they start to yearn for it because they can't afford to buy it.
The sixteenth time, they accept the fact that they will buy it sometime in the future.
The seventeenth time, they make a note to buy the product.
The eighteenth time, they curse their poverty for not allowing them to buy this terrific product.
The nineteenth time, they count their money very carefully.
The twentieth time prospects see the ad, they buy what is offering.
Herbert E. Krugman wrote "Why Three Exposures may be enough" while he was employed at General Electric. His theory has been adopted and widely use in the advertising arena. The following statement encapsulates his theory: "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.
"Exposure No. 1 is...a "What is it?" type of... response. Anything new or novel no matter how uninteresting on second exposure has to elicit some response the first time...if only to discard the object as of no further interest...The second exposure...response...is "What of it?"...whether or not [the message] has personal relevance...
"By the third exposure the viewer knows he's been through his "What is it's?" and "What of it's?," and the third, then, becomes the true reminder . . . The importance of this view . . . is that it positions advertising as powerful only when the viewer...is interested in the [product message]...Secondly, it positions the viewer as...reacting to the commercial--very quickly...when the proper time comes round.
"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 on TV. They just "put it out of their minds" until and unless it has some use . . . and [then] the response to the commercial continues."
According to Krugman, there are only three levels of exposure in psychological, not media, terms: Curiosity, recognition and decision.
The following is a list of articles and books on the subject of various theories and models of advertising.