If I showed you a page with 37 navigation links, 16 content links, 7 pictures, two ads and a search tool, would you tell me it’s too much?
Our clients often tell us, when we start working on a site redesign, that their old home page is “cluttered”, “too busy”, “too much content”, “overwhelming”, “confusing”. They don’t want their new site to fall into the same trap as the old.
There are a lot of decisions to make about what content makes it onto the home page. For now, let’s focus on one: Cognitive load.
It’s a pretty simple idea, despite the number of syllables: the more choices we face, the more work we must do to choose among them. Ever stand in a supermarket, looking at a wall of nearly-identical jars of pasta sauce? That’s what I’m talking about.
How much is too much? Should we apply the old “7 items” rule of thumb?
Review of Prior Art
Let’s look at the interface of the most wildly successful consumer product since industrial bread slicers appeared in the 1920s. The iPhone.
What’s the first thing you see after you turn on your phone? The home screen. A modest grid of icons, each representing some activity you might wish to do. Here’s mine:
That’s an iPhone 5, which added an extra row of icons to the original 2007 design. There’s a lot going on there. Let’s break it down:
To simplify things, I’m ignoring the status bar and I’ve treated the four icons in the Dock as one object. Still, I count 21 choices.
How about the larger-screen iPad? Same number of items, just less densely clustered:
This analogy isn’t perfect, of course. The phone is personal and familiar. You use it every day, and the locations of the icons become second nature. But I think it’s a good-enough analogy. The iPhone is designed to be unintimidating and easy to pick up; I’m confident that Apple’s designers spent a lot of time before settling on the original iPhone’s four-by-five grid, and it speaks to a fundamental conservatism that both the big-screen iPad and the the widescreen iPhone 5 only added a single row of icons.
If you look around, you’ll see plenty of other examples of limiting choice to improve user experience. Google could deliver hundreds of search results on the first page, but instead, offers just ten. Amazon suggests related products in batches of six to twelve. Apple has just two sizes of iPad and three iPhone models. The McDonald’s “value menu” has roughly a dozen options, no matter where in the world you go.
(Image adapted from photo by Ian Muttoo)
All these companies are fully capable of providing more choices, and if you dig deep, you’ll discover they do. Apple’s iPhone, for example, actually comes in 116 different possible combinations of model, color, network operators and storage size in the US alone.
So if a dozen or two items are managable, how about three dozen? I don’t think so – the Mac’s “LaunchPad” crosses the line into overwhelming with 36 items:
Kibitzing about Subitizing
Most people can manage up to 7 items in working memory at a time. Does this mean you can only have 7 items on a page? No, it does not. It places a cap on how many new things you can expect someone to work with, but not on how many things you ask them to recognize.
The limit on how many items in a list of choices seems to be time-based. Working memory persists for around 20 seconds. If the time between starting and finishing a task exceeds 20 seconds, it’s a high-load operation for the brain, which must start committing pieces of the work to long-term memory for storage.
Studies show the brain can count up to four objects at a glance (±2). Beyond that, our gestalt is “many” and we must subitz, chunk, or count.
Wait, what was that word? Subitz is a word psychologists use to describe when we count a group of things – too many to recognize at a glance – by breaking it down into countable groups. (It seems to be built on chunking items down into the limits of four.)
Whatever it comes from, it’s useful. It could explain why we like our phone screens have three or four columns of icons (a precedent that was set years before the iPhone) and not many more rows. Our brains can subitz a couple dozen items into less overwhelming, more managable groups, if we give it a pattern to break down.
A New Rule of Thumb
- More choices = more work
- Working memory handles 4 to 7 choices
- The brain will try to break down a dozen or two items into managable chunks
- We see evidence of using this sub-chunk pattering everywhere from iPhone to car dashboards to fine art.
Put it together, and we can mint a new rule of thumb for how much is too much:
You can easily provide 20+ distinct content objects on a screen without overloading your user, if you break it out into a few clearly structured and differentiated groups.
Earlier, I asked what you’d tell me of a page with 37 navigation links, 16 content links, 7 pictures, two ads and a search tool. Too much?
Nope. Not at all.
Two days after publishing this blog, Howard Moskowitz sent me an email:
The rest of the story.... Howard Moskowitz's career was jump started by George Miller (The magic number seven, plus or minus two). George was Chairman, Dept. of Psychology, Harvard in 1966. He accepted Howard for the Ph.D. in 1965, and after Howard passed the preliminary exams, George put Howard into SS (Smitty) Stevens' laboratory, with the prophetic statement -- Howie, you are resilient.
I couldn't be more tickled. Mr. Moskowitz, thanks for all you've done. Web usability professionals stand on your shoulders, sir. (Also, thanks as well for Cherry Vanilla Dr Pepper.)