George A Miller wrote a seminal paper back in 1956 called, “The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information”, which has often been used as the basis for many user interface design decisions including the practice of “information chunking.”
Working Memory and User Interface Design
Many tasks require us to hold a certain amount of information in our head. This is called “working memory.” This is the part of our brain that allows us to integrate and process information as well as to retrieve or recall the information when needed. When information is chunked into the magical 7 +/-2 bits, we can remember where to re-find the information again. Sticking to these limits also helps improve the scannability of a page in an application or web site.
Take these two examples. I’ve asked you to find the word “beet” in the following lists:
- apple
- orange
- banana
- strawberry
- mango
- watermelon
- plum
- carrot
- onion
- parsnip
- beet
- turnip
- rutabaga
In this list, you have to read every word to find the word “beet.” You can’t scan the list because there is no information chunking.
But if we chunk the information and get this:
- apple
- orange
- banana
- strawberry
- mango
- watermelon
- plum
- carrot
- onion
- parsnip
- beet
- turnip
- rutabaga
Why is this?
Visual Scanning and User Interface Design
It turns out that 7 +/-2 works well for scanning information. Most people don’t read carefully when they are using an application or on the web.
When information is grouped or chunked into meaningful categories, it helps people to quickly find what they are looking for. Otherwise, they need to read every item.
Some old style applications may have hundreds of tabs across the top of the app. The app becomes hard to use because they user can’t scan and find what they’re looking for. There are no logical groupings between the tabs.
Relatively early in the life of Amazon, they had a problem with organizing information because they had so many categories and an insufficient information hierarchy:
There are 9 real tabs here, but in theory they are pushed out to 10 by the “See More” pseudo-tab. The design pushed the limit of what people were able to cognitively process.
Amazon’s current design makes great use of information chunking and sticks to the 7 +/- 2 rule.
The Top area is all about technology….Android apps, the cloud, streaming, digital and even though there is no header label, (just as there were no headers for the fruits vs root vegetables), a quick scan shows you are either in the right place or that you need to drop down to the next level.
You probably don’t need to hold the layout to the left in your brain. You don’t need your working memory to navigate the Amazon site. Yet the magic number 7 rule is perfect for allowing users to easily find what they’re looking for.