Saturday, July 07, 2007

The Value of Menu Choices

How many menu choices should you use ...

"A common problem we always face is how to deal with Menu Choices… How many menus do I need? In which order should they be presented? Are the labels I’m using clear? Should I concentrate on actions callers can perform or objects they are looking for?

In particular, one that’s pretty hard to solve is the number of choices that should be offered at any time. Some developers stick to certain Human-factor derived rules such as the “5 choices maximum”. Others prefer to split them into layers so that you only offer two or three at a time, followed by the familiar “more choices” menu which then takes you to a second (or even third) set of choices. At any rate, you’ll notice there’s a common theme among all these choices: “How can I add more choices without hurting my callers too much?” (even if we don’t like to accept that’s what’s going on)

But a very intriguing question I normally have when adding a new choice is: “Are we adding more than we’re subtracting?”

It was interesting to see I’m not the only one with these types of questions. Gerry McGovern recently shared similar concerns in relationship with the internet and web applications. We are very familiar with this concept, particularly every time we ‘upgrade’ our computers or a particular application software - we know where things are, we know how to get what we want out of them, and then once we move up to an upgrade version, chances are we’re going to be welcomed by a new myriad of choices, different menus, and sometimes even different terminology for the same concepts we were already familiar with. Taken to the extreme, we run into situations like the one MS Office 2007 users are facing where interfaces are so different than it requires users to learn the mental model of the developer.

Now, taking that back to our VUI world, I’ll take one of McGovern’s examples which I think helps answer the question about the real value a choice adds.

If we were to have 100 units of “attention” we could use and we listen to 5 menu choices, it means we can give 20 units to each choice. If we were to add a new option, it would be like taking 4 units away from each of the other choices, or else you force the caller to spend more time processing the information and increasing the likelihood of them making a mistake or running into an error.

In other words, “Every time you add, you subtract attention.” says McGovern. And I’ve seen that in action both in production systems and in Usability tests: when menu choices exceed the attention capacity of a caller, there’s a point where they simply stop listening or give up."    (Continued via Voice User Interface Design)    [Usability Resources]

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