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Article posted Thursday, July 8, 2010 4:28pm

Market research studies have become one of the driving forces in the world economy. Product developers, advertising agencies, and marketers of every kind pour millions of dollars into studies that range from the amount and type of toilet paper the American consumer uses each time they visit the lavatory to how long a piece of gum lasts and whether flavor that lasts or flavor that refreshes is the determining factor for the average gum-chewing consumer.

With the plethora of seemingly useless information it is always a pleasant surprise when one of these studies not only has some relevance but also results in information that can be used in such a way that it plays an important part in our everyday lives. Some time ago, I ran across an article that piqued my curiosity and led me to further research and reading. While some of you may dispute whether this information is relevant, there can be no dispute that it has played a major, if largely anonymous role, in our lives today.

My reading led me to a study that was done in 1956. During that year a psychologist named George A. Miller published an article in The Psychological Review (vol. 63, pp 81-97) entitled, “The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information.” The gist of Miller’s article is that people generally cannot store more than approximately seven pieces of unrelated information in their short term memory without finding some way to relate them.

So let’s pause here a minute to consider this – in particular, I want you to think about phone numbers. For example, if you wanted to call the Peninsula Pulse office in Baileys Harbor and you were calling from a land line here in northern Door County, you would enter 839-2121. If you were calling from the Sturgeon Bay area on a land line you would need to enter “1” and then the area code and then the phone number: 1-920-839-2121. Of course, if you are calling from a cell phone the requirements are different, depending on your provider, but for our purposes, let’s just focus on those basic seven numbers.

Remember, Miller’s article was published 1956. So, in 1958, when today’s norm of seven digit phone numbers was introduced in Wichita Falls, KS the choice of seven numbers was anything but arbitrary. The phone company was fully aware of Miller’s research. They knew that, based on Miller’s Law, when the nephew called directory assistance to get Aunt Edwina’s phone number, the likelihood of the nephew remembering the phone number – if it was just seven digits – long enough to dial it correctly was extremely high.

Miller’s Law, however, poses distinct problems for today’s number glutted world. According to Henry Roediger, chairman of the psychology department at Washington University in St. Louis, “Every additional number you have to enter before you get to the seven digits increases the error rate. It’s called the response prefix effect.” Even the addition of just one digit causes the error rate to go up dramatically.

One way to circumvent this problem is through a memory technique called “chunking,” which involves breaking down a string of symbols into parts that can be stored in memory as though they were one symbol. In essence, “chunking” is similar to speed reading which involves recognizing whole blocks of words simultaneously rather than each word individually and, once again, the phone company tried to take advantage of “chunking” when they devised our system of phone numbers.

Just as the phone company recognized Miller’s Law when they chose seven digits as our basic phone number, they also attempted to embed chunking in the numbers by separating the first three numbers with a hyphen. And though I didn’t find any documentation to this effect, I would hazard the guess that the concept of chunking also resulted in our Social Security numbers being separated into a block sequence of 3 – 2 – 4.

However, the phone company did make one mistake in their attempt to chunk our phone numbers. For reasons that no one has been able to explain, but that has been documented in a variety of studies, memory is helped more when the first chunk consists of four digits. This phenomenon was not discovered until several years after the current numbering system was in place and even if the phone company had been aware of this they probably wouldn’t have varied their scheme: the early automated switching machines handled a three digit prefix better than four.

Of course, in this day and age, most people use their cell phones more than their land lines (if they still have land lines) and cell phones can store all our important, frequently called numbers. Thus, we aren’t really required to remember many (if any) numbers. Still, as more and more phone numbers are “used” up, phone providers are required to add more numbers, normally by creating additional area codes (i.e. additional three digit codes that precede the main seven digit phone number). However, according to Miller’s Law (and factoring in the later study regarding chunking), the better choice would be to add a digit to the area code, creating an eleven digit number sequence that would be chunked 4 – 3- 4.

In conclusion, what’s the deal with the number seven? Miller concludes his article with this observation:

“And finally, what about the magical number seven? What about the seven wonders of the world, the seven seas, the seven deadly sins, the seven daughters of Atlas in the Pleiades, the seven ages of man, the seven levels of hell, the seven primary colors, the seven notes of a musical scale, and the seven days of the week? What about the seven-point rating scale, the seven categories for absolute judgment, the seven objects in the span of attention, the seven digits in the span of immediate memory? For the present I propose to withhold judgment. Perhaps there is something deep and profound behind all these sevens, something just calling out for us to discover it. But I suspect that it is only a pernicious, Pythagorean coincidence.”