Memory is a cognitive process that enables us to store, retrieve, and apply knowledge. Educators and psychologists have spent years studying human information processing and how it relates to our ability to remember that information. Designers can take an important cue from these efforts. Related to the study of short-term memory, cognition, and perception is the theory of Miller’s Magic Number, or Chunking.
George Miller, a psychology professor at Harvard University in the 1950s, wanted to identify the limits of short-term memory. Through a series of experiments Miller discovered that the capacity for short-term memory varied among individuals, but that it was possible to measure it in “chunks.” A chunk is any single unit of information. Miller’s research revealed that the human brain could remember seven chunks, plus or minus two, in the short-term memory. It is possible to remember larger amounts of content by rechunking or recoding—the act of grouping sets of information into a single unit and then combining those units using the “Magical Number 7, +/-2.” Of course, the more familiar the subject is with the core content, the easier it is to remember greater quantities.
Chunking is also associated with memory aids such as mnemonics. Consider “Roy G. Biv,” a common mnemonic device or abbreviation for remembering the colors of the rainbow, or visible light spectrum. Each letter in the fictional Roy G. Biv’s name represents a color in the correct sequence: red, orange, yellow, green, blue, indigo, and violet. Technically that list of seven colors falls within Miller’s range of easily memorized quantities, but by rechunking the units into three parts (a first name, middle initial, and last name) we’re more likely to retain the proper order and quickly pair it with our previous knowledge of color names.
The application of Miller’s Magic Number can be easily visualized by considering something as commonplace as a telephone number. Take a quick glance at the list of 10 concurrent numbers. Easy to remember? Now look at the same numbers broken into the three-part configuration familiar to US citizens (with the area code bracketed, thanks to Ladislav Sutnar). Easier to recall? That’s because the information has been rechunked into just three sets.
Miller’s Magic Number is often related to the use of mnemonic devices. Here, the colors of the visible light spectrum are reduced to a simple name, Roy G. Biv. Each letter represents a specific color, listed in the correct order.
Design for retention: Make aesthetic and communication decisions that target every stage of the memory process. Use contrasts and color to attract immediate notice. Create associations with familiar subjects to help the user store the information. And provide parsed, accessible chunks of content for easy retrieval.
Make it easy: Use Miller’s Magic Number to make complex information sets easier for your user to access, understand, and recall. Break complicated or lengthy content into smaller chunks, always remembering “7, +/- 2” as your guide. Then utilize design continuity to link those sections into a broader message.
1. This parse is excerpted from The Information Design Handbook by Jenn + Ken Visocky O’Grady
2. To read the original paper on chunking, see “The Magical Number Seven, Plus or Minus Two: Some Limits on our Capacity for Processing Information,” by George A. Miller, The Psychological Review, 1956, vol. 63, pp. 81-97.
3. Learn more about Information Design pioneer and AIGA Medalist Ladislav Sutnar through this biographic sketch from Steven Heller, or pick up a copy of Sutnar’s newly reprinted classic Visual Design in Action