Laws of UX, 2nd Edition

Chapter 3. Miller’s Law

The average person can keep only 7 (± 2) items in their working memory.

Key Takeaways

• Organize content into smaller chunks to help users process, understand, and memorize easily.

• Remember that short-term memory capacity will vary per individual, based on their prior knowledge and situational context.

• Don’t use the “magical number seven” to justify unnecessary design limitations.

Overview

It’s likely that many designers will have heard of Miller’s law, but there is also a high probability that their understanding of it is inaccurate. This commonly misunderstood heuristic has frequently been cited as justification for design decisions such as “the number of navigation items must be limited to no more than seven” and so forth. While there is value in limiting the number of options available to users (see Chapter 4, “Hick’s Law”), it is misleading and inaccurate to attribute such dogma to Miller’s law. In this chapter, we’ll explore the origins of Miller’s “magical number seven” and the real value Miller’s law has to provide to UX designers.

Origins

Miller’s law originates from a paper published in 1956 by cognitive psychologist George Miller titled “The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information.”¹ Miller, a professor at Harvard University’s Department of Psychology, discussed in his paper the coincidence ...