Wednesday, June 04, 2008

Expectations & Usability: Consistency

How to use consistency in user interface design ...

"Recently, I've talked about why expectations drive usability and how industry standards and habits create expectations. Once a visitor reaches your website, though, you also start to set your own expectations. You would think that the expectations you set yourself would be the easiest to meet, but sadly, that doesn't seem to be the case. Many of the most common website usability problems I come across boil down to violating internal consistency. Below are some common consistency problems and how to avoid them:

Use Consistent Navigation
The position and intent of navigation is probably one of the most important expectations a website designer can set. Once a visitor decides to stay on a site long enough to understand the basic "map", one of the easiest ways to lose them is to change that map. Here are a few things to watch out for:

Avoid Splash Pages
I like to think that every technique has its place, but I have to admit that I welcomed the demise of the splash page. Having a home-page with a very different design and navigation from the rest of a website is like having two home pages; visitors have to stop and figure things out twice. That's twice as many chances to lose your customers.

Avoid Moving Targets
Early in web design, people experimented with navigation that changed from page to page. For example, people used menus that removed the current page's button in an attempt to reduce clutter and be user-friendly. I'm all for experimentation, but spatial cues are very important for web users. Once a button appears in one place, they expect that button to stay in place.

Make Links Obvious
Basic text links are critical to good navigation. This is a general usability issue as well as a consistency issue, but choose a link style that's clear (I recommend either blue or underlined) and once you choose one, stick to it. Also, be very careful not to use your link style in other, non-linked situations. I'm amazed how often I see people using black, underlined text for both links and emphasis on the same site.

Use Consistent Styles
CSS-based design has been a big help in this department, but it's important to keep your text styles, and the intent of those styles, consistent throughout your copy. Otherwise, your site starts to look and feel schizophrenic.

Emphasize Consistently
Emphasis can be an important element of both instructive and persuasive copy, but if you start bolding some text, italicizing other text, and have other words in red, green, and hot pink with stars next to it, people are going to get confused. Pick an emphasis style and stick to it.

Don't Overemphasize
This is more of a general usability issue, but don't emphasize everything. I've seen web pages where 40% of the copy was bolded, underlined, or italicized. If you try to draw attention to everything, you effectively draw attention to nothing.

Use Header Tags
Basic HTML header tags (H1, H2, etc.) are good for consistency, usability, and even search-engine optimization. Create a sensible hierarchy of headline styles and stick to them. Using pre-defined tags will help you stay consistent and also make writing copy easier."    (Continued via User Effect)    [Usability Resources]


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