How many items can you hold in mind at one time before they start tumbling out of memory? Cognitive scientists have determined that the most we can remember of a list of unfamiliar items is between 5 and 9 items. Or, about 2 seconds worth of what we can repeat, out loud or to ourselves.
Decades of research have firmly established these limitations. Happily, there’s a way around this cap on memory. It happens automatically, as well as deliberately. It’s called “chunking.”
The Magical Number 7 Plus or Minus 2
If you've heard “chunking” before, then the chances are you have associated the number 7 with the term.
George A. Miller, one of the top scientists of the 20th century, in his classic 1956 paper, "The Magical Number Seven, Plus or Minus Two," coined the terms "working memory" and "chunking." He discovered that the number of digits people could hold in mind before their memory overloaded was remarkably consistent across all people. So pervasive was this number that his famous article opened with, “My problem is that I’ve been persecuted by an integer.”
Miller also observed that people would remember more items if they were grouped, or chunked. The most common example of chunking is the telephone number. Remembering ten digits, such as 5 4 1 5 5 5 3 2 2 6 is hardly possible, but if the ten digits are chunked into three units, 541-555-3226, remembering all ten numbers is easily done. The 10 digits then become just 3 chunks to remember.
If you think you can hold more than 7 digits in memory, most likely you have chunked the digits.
Chunking and Learning
Chunking is a fundamental operation in learning. Bits of information combine to form a chunk, chunks cluster with other chunks, and so on. Because of this consolidating process, a chunk can represent a great deal of compressed information. Think how much data you’ve chunked with the words, “United States.”
When kids learn to read, they must first link a letter’s name with the correct squiggly-line depiction. The letter’s name must then couple with the sound(s) it makes. Strings of sounds must connect to “read” a word. Imagine how much easier it is for kids to “sound out” words they’ve heard many times; otherwise, the stringed-together sounds don't make much sense.
Familiar words are much easier to hold in working memory than unfamiliar words. Because the word "pig" is familiar, it takes up very little mental space. Contrast “pig” with "babirusa." What? “Babirusa” is not just unfamiliar, its four syllables worth of unfamiliar, which takes much more effort to keep in memory. But if a babirusa is familiar--maybe you were enchanted by one at the zoo, or you grew up in Indonesia--it takes as little effort to hold in mind as does “pig.” Being familiar with many words gives children a working memory advantage when learning to read.
Chunks of knowledge build up background knowledge in our long term memory. Chunking is how we hack the limits of working memory.
Chunking and Expertise
Researchers discovered that experts’ knowledge is chunked quite differently than novices’. Andreas Ericsson, who discovered and coined the 10,000 Hour Rule, used chunking differently from George A. Miller’s reference to groupings of digits or unfamiliar items.
Ericsson noticed that chess masters retrieved knowledge from long term memory around meaningful game patterns that novices did not see or understand. He discovered that experts in general comprehend the major problem types in their fields and retrieve only information relevant to the specific problem they are considering. They skillfully avoid overloading their working memory with oodles of related but unorganized ideas, allowing them to think about enormous amounts of information with relative ease. It takes years of deep thinking about a domain of knowledge to chunk like an expert.
The path of gaining deep knowledge goes from the modest beginnings of hearing words in early life, to chunking bits of general knowledge into useful clusters, to building a storehouse of topic-rich background knowledge, to thinking about problems at the right level of difficulty, and to organizing knowledge in meaningful patterns along the track toward expertise.
How Can Parents Build Skills To Use Chunking More Effectively?
We hope our kids get assigned to teachers who explain well, who manage the dynamics of chunking and working memory with finesse. Like teachers, parents are also in the business of managing kids' chunking and working memory processes, even if they don't fully realize it. There are many ways parents can use chunking more skillfully with their children. Here are a few.
Expose your kids to many chunks of information
You already do this, but if you do it with greater awareness, your kids will benefit. Notice what interests them and add a few bits of information about it. Bit by bit is best, otherwise you’ll overload them. Kids with a treasure of chunked general knowledge find school work more intriguing simply because familiar topics pique interest.
Don't confuse an overloaded working memory with “not minding"
Certainly kids defy our direction at times. On the other hand, sometimes parents mistakenly think their kids are misbehaving when really their memory just overloaded. What seems like a simple set of instructions to a parent, for a kid might involve too many steps. Kids don't reach their full capacity of working memory until the age of 11 or 12.
Teach kids how to chunk deliberately
Show kids how chunking information into groups makes remembering easier. Also, when kids are learning something new, ask if the new information reminds them of anything they already know. Associating is chunking. Or, just make a connection for them, by telling how a new piece of information is like something they already know. Tying new information to what is already known is chunking.
This article is just a teeny chunk of what there is to understand about this topic. Below are resources to learn more.
"How Knowledge Helps," by Daniel T. Willingham, describes the learning advantages of background knowledge and mentions chunking eighteen times in the explanation.
"Working Memory and School Performance," a Psychology Today article by Torkel Klingberg, author of two books: The Overflowing Brain: Information Overload and the Limits of Working Memory and most recently The Learning Brain: Memory and Brain Development in Children (Oxford University Press).
"A Wealth of Words," a City Journal article by E. D. Hirsch explains brilliantly about chunking and reading, saying, "Words are fantastically effective chunking devices."
"How to Be a Better Test Taker," a New York Times article by Annie Murphy Paul, says, "Find associations and think in chunks."
"The Magical Number Seven, Plus or Minus Two," the classic article by George A. Miller, Psychological Review.
"The Magical Mystery Four: How Working Memory Capacity is Limited, and Why?" another classic article on working memory, by Nelson Cowan, NIH/NLM.
Chapter 2 and 6 of Why Don’t Student’s Like School, Daniel T. Willingham, a PCM Top Ten Book for Parents.