Krug's Definition of Usability
- Useful: Does it do something people need done?
- Learnable: Can people figure out how to use it?
- Memorable: Do they have to relearn it each time they use it?
- Effective: Does it get the job done?
- Efficient: Does it do it with a reasonable amount of time and effort?
- Desirable: Do people want it? and recently even
- Delightful: Is using it enjoyable, or even fun?
Every question mark adds to our cognitive workload, distracting our attention from the task at hand. The distractions may be slight but they add up, especially if it’s something we do all the time like deciding what to click on.
Here’s the rule: If you can’t make something self-evident, you at least need to make it self-explanatory.
Three Facts About Web Pages
Fact 1: We don't read web pages. We scan them. — We focus on words and phrases that seem to match (a) the task at hand or (b) our current or ongoing personal interests and (c) the trigger words that are hardwired into our nervous systems (e.g. "Sex" or our own name).
Fact 2: We don't make optimal choices. We satisfice. — We choose the first reasonable option, a strategy known as satisficing.
- Web users don't look for the best choices because they are (a) usually in a hurry and (b) guessing is more fun (see Variable Rewards)
Fact 3: We don't figure our how things work. We muddle through. — An inefficient and error-prone method.
Billboard Design 101
- Conventions are your best friends — innovate when you know you have a better idea, but take advantage of conventions when you don’t.
- Clarity trumps consistency — if you can make something significantly clearer by making it slightly inconsistent, choose in favour of clarity
- Create effective visual hierarchies
- Break up pages into clearly defined areas — eye-tracking studies show users decide very quickly in their initial glances which parts of the page are likely to have useful information and then rarely look at the other parts
It doesn’t matter how many times I have to click, as long as each click is a mindless, unambiguous choice.
- The rule of thumb might be something like “three mindless, unambiguous clicks equal one click that requires thought.
Get rid of half the words on each page, then get rid of half of what’s left.
"Omit needless words. Vigorous writing is concise. A sentence should contain no unnecessary words, a paragraph no unnecessary sentences, for the same reason that a drawing should have no unnecessary lines and a machine no unnecessary parts." — William Strunk (see The Elements of Style).
Your objective should always be to eliminate instructions entirely by making everything self-explanatory, or as close to it as possible.
Things You Need to Get Right
As a rule, the persistent navigation can accommodate only four or five Utilities—the ones users are likely to need most often.
Test for good web navigation — You should be able to answer any of these questions if on any page of the site:
- What site is this? (Site ID) What page am I on? (Page name) What are the major sections of this site? (Sections) What are my options at this level? (Local navigation) Where am I in the scheme of things? (“You are here” indicators) How can I search?
As quickly and clearly as possible, the Home page needs to answer the four questions I have in my head when I enter a new site for the first time:
- What is this?
- What can I do here?
- What do they have here?
- Why should I be here — and not somewhere else?
Then, the fifth question: Where do I start?
Making Sure You Get Them Right
Designers enjoy pleasant visual experiences. And developers tend to like complexity. The result is that designers want to build sites that look great, and developers want to build sites with interesting, original, ingenious features.
- There is no such thing as the average user.
- Debates between product teams are solved by user testing.
Usability test — watching one person at a time try to use something (e.g. prototype, web site, sketches) to do typical tasks so you can detect and fix the things that confuse or frustrate them.
Recruit loosely — try to find users who reflect your audience, but don’t get hung up about it. Instead, loosen up your requirements and then make allowances for the differences between your participants and your audience.
- See Nielsen Norman Group’s free report How to Recruit Participants for Usability Studies.
- See Krug's usability test script.
Resist the impulse to add things. When it’s obvious in testing that users aren’t getting something, the team’s first reaction is usually to add something, like an explanation or some instructions. But very often the right solution is to take something (or some things) away that are obscuring the meaning, rather than adding yet another distraction.
Larger Concerns and Outside Influences
Note that while people love to make comments about the appearance of sites—especially about whether they like the colours—almost no one is going to leave a site just because it doesn’t look great.
Know the main things that people want to do on your site and make them obvious and easy.
Unless you’re going to make a blanket decision that people with disabilities aren’t part of your audience, you really can’t say your site is usable unless it’s accessible.
- Don’t use small, low-contrast type.
- Preserve the distinction between visited and unvisited text links.
- Don’t float headings between paragraphs.
Image credits: Don't Make Me Think by Steve Krug