Chunking

Think about how you might rehearse a 10-digit phone number. You’ll probably recall the three-digit area code, followed by a set of three more numbers, then the final four. While you might not be aware of it, separating the number into three pieces of information (123-456-7890) rather than trying to recall a long string of ten pieces of information (1234567890) is a process called chunking, which has recently become a popular idea for understanding how the mind works.

Chunking refers to our ability to improve short-term memory by grouping – into “chunks” –  information to reduce the overall number of items assigned to the act of remembering. For example, if asked to remember this sequence of twelve letters: I, B, M, F, B, I, C, I, A, I, R, S, one would benefit by considering the same sequence in a chunked format: IBM, FBI, CIA, IRS. Given the limited capacity of short-term memory, by chunking information, one puts less strain on their memory while still storing the same content.

Long-term Memory: Vast storage of information held indefinitely. It is considered the final stage of memory processing.

Short-term Memory: Limited storage of information held temporarily, in an accessible state, though not always processed consciously. Sometimes also referred to as “active memory.”

Working Memory: With a large overlap with short-term memory, working memory relates to the immediate storing and processing of information that’s used to plan or carry out a behaviour. How it’s precisely distinguished from short-term memory is debated. Some might consider it synonymous with short-term memory, while others might argue that it’s the attention related component of short-term memory, whereby conscious processing is integral to the concept.¹

In 1956, the psychologist George Miller published an article in the Psychological Review on the limits on our capacity to immediately process information.² From the article emerged Miller’s “magical number seven.” Miller argued that the limited capacity in short-memory processing was bound by seven, plus or minus two chunks of information. To refer back to the 10-digit phone number again, remembering the number as ten unique chunks of information would exceed the limits of short-term memory. However, storing the phone number as three chunks of information, would be within the limit. This figure of 7 ± 2 has also been referred to as “Miller’s Law.” Miller’s article would go on to become a seminal piece of work in cognitive psychology, having been cited over 33,000 times, making it one of the most cited papers in the field.

Although it doesn’t really take a psychology degree to know that our short-term memory capacity is in fact limited, work on chunking has refined these limits and continues to broaden an in-depth understanding of such limits. This level of understanding has been applied in cases of memory deficiencies, such as Alzeihmer’s Disease. In one study, researchers found that chunking techniques were able to improve working verbal memory in individuals with mild Alzeihmer’s.³

Chunking has also been leveraged as a memory tool for a general audience, offering a technique that individuals such as studying students or serving staff can use to store more information in their short-term memory. Ideas around chunking have also been acknowledged from a product development standpoint. By recognizing people’s limits in short-term and working memory, user experience can be improved by presenting content in a way that is easily processed by a user.

It is rare to see criticisms of chunking, however, no concept in psychology has existed without being challenged. Nelson Cowan, a psychologist at the University of Missouri, pointed out in 2015 that there was essentially a 40-year hiatus on studying capacity limits in working memory following Miller’s paper in 1956.⁴ Cowan suggests the lack of further research building on Miller’s work was due to the fact that he had written his paper using fairly humorous language, highlighting that Miller had written having “been persecuted by an integer” in reference to the magic number seven. In his conclusion, Miller drew parallels to the ubiquity of chunks of seven: the seven seas, the seven deadly sins, the seven wonders of the world, etc. He questioned whether “there was something deep and profound behind all these sevens,” but suggested that it was merely a “pernicious, Pythagorean coincidence.”

Cowan believes this language was influential in stymiing research on chunking, noting that, “scientists shy away from topics that could make them the butt of a joke, so research on possible real commonalities between the phenomena was thereby discouraged, inadvertently I would assume.” Cowan would go on to advocate for further progression of Miller’s research and chunking theory, as in its current state, there are still many unanswered questions. The nature of capacity limits in short-term and working memory for example – whether working memory stores chunks of information discretely or fluidly –  is an area of research that didn’t garner much attention until several decades after Miller’s original paper and stands to benefit from further exploration.

Other criticisms around chunking theory revolve around Miller’s “magic number seven.” Some experts in domains such as design, argue that the 7 ± 2 figure is a misleading heuristic, suggesting that a smaller number would be more appropriate in design contexts as Miller’s Law relates to the upper bounds of short-term memory. Design settings such as user experience (UX) benefit from making things easier for a user, so pushing the upper bounds of short-term or working memory may not always be ideal as it would presumably make a process comprehensible though still demanding.⁵ It is important to note however, that this issue does not actually challenge the efficacy of chunking but rather the concept’s application and interpretation.

1. Cowan, N. (2008). What are the differences between long-term, short-term, and working memory?. Progress in brain research, 169, 323-338.
2. Miller, G. A. (1956). The magical number seven, plus or minus two: Some limits on our capacity for processing information. Psychological review, 63(2), 81.
3. Huntley, J., Bor, D., Hampshire, A., Owen, A., & Howard, R. (2011). Working memory task performance and chunking in early Alzheimer’s disease. The British Journal of Psychiatry, 198(5), 398-403.
4. Cowan, N. (2015). George Miller’s magical number of immediate memory in retrospect: Observations on the faltering progression of science. Psychological review, 122(3), 536.
5. LeCompte, D. C. (1999, September). Seven, plus or minus two, is too much to bear: Three (or fewer) is the real magic number. In Proceedings of the Human Factors and Ergonomics Society Annual Meeting (Vol. 43, No. 3, pp. 289-292). Sage CA: Los Angeles, CA: SAGE Publications.