The concept of the magic number seven, plus or minus two, has a long, revered place in the history of psychological research. It has been well known since the 19th century when a little observational experiment was done by Scottish philosopher, William Hamilton. Hamilton noted that whenever a handful of marbles were thrown onto the floor, the placement of only about seven of the marbles could be remembered without confusion. G.A. Miller, a Princeton University psychologist, wrote his famous paper, "The Magical Number Seven, Plus or Minus Two," in 1956. For many years, this was the most cited non-statistical paper in psychology. Miller's contention was precisely the same as Hamilton's: most of us can hold in short-term memory approximately seven units of information.
This cognitive process is called digit span, or alternatively, sequential processing. It measures how many digits can be taken in through the eyes or ears and repeated in correct order. The test offers insight into attention span and organization of information. On its most fundamental level, it is a memory test, asking the performer to utilize a specific memory system in the brain that we call short-term memory. It is performed most simply in the form of a tester saying three to seven numbers at one-second intervals, and asking the applicant to repeat back the numbers.
As well as being a memory test, it is also an ordering technique. If we don't remember the order of information, processing the information would be a cognitively chaotic experience. We might be able to remember all the numbers in a telephone number, for instance, but if we don't know the order of the numbers, we won't be able to reach the person we want to call.
Sequential processing takes place almost every time you attend to a new source of information. In fact, it happens right now as you are reading these lines. Think about the complexity of the task of reading. First you have to recognize the words (receiving the information); then, you have to hold each word in memory long enough to link one word to the next (holding the information); next, you have to ascribe meaning to the linked words (processing the information); finally, you use the meaning you have ascribed to the words to make a decision about how you want to use the information -- do you want to use it to further the progression of civilization, or do you want to throw it in the garbage can -- (utilizing the information)?
It is not mere coincidence that phone numbers have been seven digits since 1959, when AT&T changed over from place-name plus digits to all-digit dialing. So, instead of University 7-8634 (and yes, I am old enough to remember those days -- that number was my Cousin Carol's phone number), the number became 867-8634. When phone numbers included a word, they were easier to remember than they are now. (The newest addition of needing to dial area codes, even when you are calling a number within the same area code, is not an additional memory burden however; the three digits that comprise the area code are already familiar to us; they have been cycled into long-term memory storage, and their familiarity means that they are "chunked" not as three separate items, but as one item of information.)
Traditionally, researchers have thought that as the brain grows, from birth onward, the child can increase his digit span by one item per year. A one-year-old can repeat back one number; a two-year-old can repeat back two numbers; a five-year-old can repeat back five numbers. It has been thought that the ability to retain sequential items in short-term auditory memory ends at seven years of age; thus, prevailing intellectual wisdom (and Miller's research) has been that most people can repeat back about seven sequential items -- plus or minus two, referred to as "7 + or - 2"; yet, as in all things, some people do a little better, and some do a little worse -- but the magic number seven is the average, and describes the ability of most of us.
Or does it? Perhaps in 1956, when George Miller wrote his paper, the average digit span memory was seven; but it is likely that average number is lower in today's population. With external electronic devices replacing our internal memory systems, we are asking our brains to do less memory-work, and thus, it is likely that our brains have become less efficient or skilled at memory-work. Probably more of us function on the low end of the seven plus or minus two scale than the high end. In giving a number of people a digit span test, I have found that for many, memories are taxed in trying to repeat back seven full digits.
Since Miller's publication, there has been a wealth of research on digit span, and the correlation of sequential processing ability with intelligence and over-all cognitive functioning. Digit span is taught and used as a standard diagnostic tool in all IQ testing as well as in comprehensive cognitive evaluations. It has been shown that digit span has a high correlation with IQ. A 1996 study compared digit spans and standardized test scores for grades K through 12, and showed that there is, on average, a 3.1 year grade-level-difference in achievement between an auditory digit span of five and an auditory digit span of six. (This would be enough, for example, to bring seventh-grade work up to tenth-grade level.)
It is fair to say that any individual with an auditory or visual digit span under seven digits is functioning with a handicap. Low auditory and visual sequential processing ability is a major contributing factor in almost all learning disabilities.
You can assess your own sequencing ability by simply having someone say a random assortment of numbers to you, one digit a second. Then you repeat the numbers. Start with four digits, and with each success, build up to the next level. When you top off at whatever number you achieve, then continue with the experiment, but now repeat the digits fed to you backwards. It's much harder, but challenges your brain to not just remember, but to actually manipulate items in short-term memory, to re-position them.
In my next blog, you will read how one man, Bob Doman (Director of the National Association for Child Development), has made a game-change for sequential processing by challenging one major assumption that all researchers and clinicians had previously made -- that the digit span capability of an individual is a fixed ability (like over-all IQ).
Until Doman, psychologists assumed that digit span capability -- once it topped off at the level achieved around age seven -- would not vary from year to year, or even from circumstance to circumstance. Yet, Doman has demonstrated with tens of thousands of people that digit span capability can be improved, and when it is, global changes in functioning are witnessed.
If you scored under seven on your little digit span assessment, you will want to know how to improve your score. If you scored seven, you could move from normal cognitive functioning to superior cognitive functioning. This one simple little exercise can change your entire cognitive functioning, not only making you smarter, but more efficient, more focused, more creative, more integrated, with more functional competence, as well as being a better communicator. Sequential processing is one of the exercises that is performed in the Brainercize series of classes developed through the coordinated efforts of myself with leading cognitive psychologists, offered at my NYC spa, La Casa Day Spa. For a recent write-up of the program, go to http://www.dayspamagazine.com/blogeditors/?p=1003
Therese Borchard: Flex Your Moral Muscle: God Can Change Your Brain
Alvaro Fernandez: Top 15 Brain Fitness Articles of 2008
Alvaro Fernandez: Top 7 FAQs On Brain Fitness And Neuroplasticity
Gretchen Rubin: 12 Surprising And Productive Brain Exercises
7 numbers in a phone number, 5 or 9 zip code numbers, 9 Soc Sec numbers, 7 continents (doesn't have to be divided up that way), 7 seas (same), 5 fingers, but asking the entire population to count on all fingers at once will lead to trouble. 8 characters is a common minimum password requirement, 7 days of the week, 8 Brady Bunch kids, 7 dwarves, etc.
And the Holy NFL violated the rule and divided into divisions of only 4 teams, and now is under intense criticism because a group of only 4 teams might produce only 4 bad teams, leaving out better teams from other divisions.
PS. Six Pack, 6 cylinders, 5 card draw, 7card stud, 6 feet under, 6 Too Big To Fail Banks, Jackson 5, Chicago 7, etc.
If someone were to say seven *ideas* in a row--I bet many of us could remember 7 of them easily, and much more--8,9, and 10 before stumbling.
We can remember all the main points in his article which was many paragraphs long and we could even read 7 or more full articles and remember them well enough to repeat their gist, without much trouble.
This type of intelligence seems much more important and complex than what is measured in the 7-digit test, seems to me.
So I'm not sure what the 7-span test is measuring, despite its correlation to grade level.
Ever since then, in order to learn anything new, I have to forget something.
Two recently pieces of research, one done as a result of a broadcaster’s whim, have cast light on things that amygdalae seem to influence. [...]http://silverbuzzcafe.com/?p=15052
I can remember my grandmothers phone number but i could not tell you my wifes !
It does not work any more to use letters to spell out the number - my cell phone does not have the corresponding letters on the keypad. Cigna is my health insurance, and I had to call them - I went on their web site to get the number and they list 1-800-CIGNA24. I had to find a picture of a phone keypad in order to figure out the numbers.
what i wonder is who does better the auditory or the visual memory storer/retriever?
On the other hand, once I've got something - numbers in particular - committed to long-term memory, it seems to stay there. I can still remember every phone number (including the word prefixes), address and license plate number I've ever had. Talk about useless knowledge.
I remember all the addresses I've ever had in two countries and had a lot of fun showing my kids where I've lived in my life when Google Earth came out. It even relieved me to discover that I was remembering things right.
Names? Not so much.
It was when I got outside of that area that I ran into trouble. Other parts of the UK had (at the time) 4-digit area codes followed by a 6-digit telephone number. There are loads of different area codes in the UK so more often that not, if I was phoning someone outside of London, I had to dial a 10-digit number. I found it ridiculously hard to commit non-London numbers to memory because, to me, the number pattern felt 'wrong.'
Then, in the '90s, area (dialling) codes everywhere were made even longer by inserting a '1' in the sequence. For example, if your previous one had been '0788,' it now became '01788,' followed by a 6-digit number. I had to start all over again, getting used to an 11-digit number sequence (you wouldn't think just adding that extra '1' would make a difference, but it did for a while).
The brain is a funny thing.