De La Soul says 3 is the magic number.
In the design world, however, the magic number is 7 plus or minus 2 (so more of a magic range, I suppose). The reason is simple: apparently people can only remember or process 7 +/- 2 pieces of information at a time (George A.Miller, 1956). So, we IAs set about ensuring our designs had only 5 to 9 options in a navigation system or 5 to 9 tabs on a screen.
Well, that magic number has been consigned to the scientific rubbish bin by all sorts of psychologists since then, from Cowan in 2001 (who now names 4 as the magic number for working memory capacity) to Miller himself (who tries to distance himself from the misreadings of his original paper).
Applied to information architecture, we talk about breadth vs. depth in navigation and menu system design for websites. Which is better? A site that is broad and shallow so that everything is within just a few clicks? Or a narrow and deep site that reduces the number of options at each step, but results in much longer journeys to the content?
Rather than relying on the changing nature of mystical numbers, I focus on the underlying rule of thumb or design heuristic instead:
Decision paralysis is also known as the paradox of choice, feature fatigue, or Hick’s Law. But as the incredibly smart book Nudge says, “As choices become more numerous… good choice architecture will provide structure, and structure will affect outcomes.”
Good choice architecture applied to facet and navigational design balances the following competing issues:
- How familiar your lawyers are with the terms or content being explored
- How often your lawyers will use the UI
- Whether the menus appear on already cluttered pages (although balance that with successful link-rich studies)
- Whether you can chunk your tabs or options into fewer intuitive link clusters (without creating many sub-sub-menu layers in your navigation)
So, unless you are part of the brilliant De La Soul posse and can get away with singing about magic numbers, I recommend you apply the underlying heuristic instead. Focus on looking for the unique decision paralysis point on your UI with your users.