Limiting the number of menu tabs or the number of items in a dropdown list to the George Miller’s magic number 7 is a false constraint. Miller’s original theory argues that people can keep no more than 7 (plus or minus 2) items in their short-term memory. On a webpage, however, the information is visually present, people don’t have to memorize anything and therefore can easily manage broader choices.

For example, research shows that broad and shallow menu structures may even work better than deeper menus. Also, link-rich e-commerce homepages, like that of Amazon with 90+ product category links, are found to be more usable than homepages with only a few links.

Articles debunking the myth of 7+/-2:

• The Wikipedia article on Miller’s Law states that the law only applies to humans’ working memory. - The Magical Number Seven, Plus or Minus Two
• Even George Miller was shocked to see how badly his original concept was misinterpreted, saying that “The point was that 7 was a limit for the discrimination of unidimensional stimuli (pitches, loudness, brightness, etc.) and also a limit for immediate recall, neither of which has anything to do with a person’s capacity to comprehend printed text.” - See his letter
• Jakob Nielsen says that, although short-term memory is indeed very important when designing web pages (ie. indicating visited links, showing help content without leaving the page), it’s misleading to use it for menu design. - Short-Term Memory and Web Usability
• Edward Tufte says that “These studies on memorizing nonsense then led some interface designers to conclude that only 7 items belong on a list or a slide, a conclusion which can be sustained only by not reading the paper. In fact Miller’s paper neither states nor implies rules for the amount of information to be shown in a presentation.” - The magical number seven, plus or minus two: Not relevant for design
• Recent research suggests that the broad top-level menus work best since they’re the most efficient and least error prone. - Breadth vs. Depth
• A GUUUI article details why apparent simplicity can sometimes result in higher complexity. The article also debunks the 7+/-2 myth. - Balancing visual and structural complexity in interaction design
• A ClickZ article explains why 7 might be magical but isn’t based on science, Human Factor also discusses it in Reducing reliance on superstition.
• So if you have many options, you don’t have to limit their number to seven on a user interface. However, you should still think about every option, consider whether you need it or not, as more choices don’t always lead to higher satisfaction.

Zoltán Gócza