Cognitive load and the rule of seven (or how many is too many)


Ok, so I have done some deep researching about “how many is too many” (as far as links and information bits on a page) and I thought I would share some of this with the Digital Web Magazine readership. Most of my research pointed to this paper, The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information by George A. Miller, published in 1956 mind you.

To summarize, “The span of absolute judgment and the span of immediate memory impose severe limitations on the amount of information that we are able to receive, process, and remember.” Therefore the number of links or bits of information should be kept below seven.

However, my esteemed colleague, Christina Wodtke, was quick to point out that there is much proof on the contrary to this theory: Web Page Design: Implications of Memory, Structure and Scent for Information Retrieval and The Myth of quot;Seven, Plus or Minus 2″, etc. Upon her advice I spoke with Victor Lombardi, known expert in the field of Information Architecture, User Experience and Research. He summarized his findings in this area for me quite nicely:

  1. Breadth vs. depth is the wrong question to ask, it’s irrelevant to the user experience
  2. The number of links and density of links is what people experience
  3. Different audiences and applications will want different a different number and density of links
  4. Once you find the number and density (guess + usability testing) you just prioritize information:
    1. some things will fall naturally into taxonomies
    2. some will fall naturally into task-based navigation
    3. the rest is probably all about priority, so as you reach your number and density limit, push lower priority stuff to the next level down

Keith also has some pretty good information on this subject in his article The One Magic Rule of Web Design.

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