100 Things: Every Designer Needs to Know About People

20. People Remember Only Four Items at Once

If you’re familiar with usability, psychology, or memory research, you’ve probably heard the phrase “the magical number seven, plus or minus two.” This refers, actually, to what I would call an urban legend: George A. Miller (1956) wrote a research paper showing that people can remember from five to nine (seven plus or minus two) things, and that people can process seven plus or minus two pieces of information at a time. So you should only put five to nine items on a menu, or have five to nine tabs on a screen. Have you heard that story? Well, it’s not quite accurate.

Why It’s an Urban Legend

Psychologist Alan Baddeley questioned the seven plus or minus two rule. Baddeley (1994) dug up Miller’s paper ...