When I was doing the design for the
BTO Support Center website, I had some troubles explaining to some coworkers why helpful text shouldn't be added to explain the interface. At the time, I couldn't explain it well, but now that I've thought about it a while, I think I have a better way to describe it.
My new argument assumes that the interface is explorable. Let's start with that.
If a user is comfortable with a user interface, they will happily play with it until they get it to do what they want. This is called an explorable interface, and it's required in any good interface. For example, I'm typing this on the blogging software's built in editor. I've never used this editor before, but the cost of just pushing buttons randomly on it is low. I can undo them easily, so I'm not worried about pushing the wrong thing. The editor doesn't normally pop up a useless dialog box that I have to get rid of, so pushing the wrong button is unlikely to waste much of my time. It is laid out in a way that explains what buttons are relevant, so I don't even have to scan most of the web page. The cost of not knowing what I'm doing is low, so I've never read most of the text on the page.
The economist Herbert Simon described this behavior as "
satisficing". This is a combination of satisfy and suffice, and Herbert Simon used it to describe people's behavior when confronted with a choice that is expensive to resolve. If the cost of reading an entire web page to find the optimal solution is expensive, then people are perfectly happy to use the first thing they find that might work. The interface designer has to do a lot of work to make sure that the first thing they find is the correct one.
In an explorable user interface, users don't have to figure out exactly what the designer was thinking. They don't have to read every bit of text on the dialog. They can just pick a button that might do what they want and push it. This, it turns out, is often substantially cheaper than trying to understand the interface completely. After all, you can just undo it afterwards.
Once you understand this, a bit of text to describe your interface is clearly the wrong answer. A user will not actually read the text on the web page if exploring might work. If exploring doesn't work, the user will become frustrated rather than resorting to your helpful bit of text. In some cases, they will be perfectly happy to assume that your interface doesn't support the option they were hoping to find.
Don't explain your interface. Make it easy to explore.
I'm also against too much text or popup dialogs to explain interfaces. It definitely slows the user down and makes using a program a boring task, which might make them never to come back again. I like clean designs and fast responding interfaces that work as you think they would, not as they say the should.
