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Chapter 3: Don't Impose: Respect Mental Effort

Let's assume you agree that clicks are a precious commodity and you're trying to remove them from your technology. It may have crossed your mind that one way to do so is to make a button for every possible variation on every task, and then make all those buttons visible from the main screen. Then every task is one click away! We'd give you an A for effort, but it won't work. It's true that an interface like that would reduce physical effort, but the cost would be mental effort. Even if your technology lets people do only 100 things, it would be far too difficult to pick the one right button. Just as you should reduce your customers' physical effort, you should also reduce their mental effort. You want to leave them as much mental energy as possible so they can flow with their task and forget about the technology entirely.

Every now and then, a product comes along that greatly reduces mental effort. PVRs such as TiVo, Replay, and UltimateTV are such an example. Among other things, PVRs allow you to record television shows and replay them later. Instead of asking what time and channel you want to record, PVRs ask you what television show you want to record. That's just how you would ask a butler: "Please record East Enders for me," not "Please record Mondays and Tuesdays at 7:30 p.m." You can ask a PVR to record a particular episode or all episodes. If you do the latter and the show is moved to a new time or station, you don't even have to know about it. The PVR continues to record it. If the show is cancelled one week, it won't record that week. PVRs minimize mental effort by allowing you to focus on the thing you care about (which show to watch), and not irrelevant aspects of the technology (the channel and schedule).

With most technology, you won't be able to reduce mental effort that much, but you can do so in many small ways on many tasks. In his book Don't Make Me Think!, Steve Krug calls it "thinking" any time you have to stop for a split second to figure out the interface rather than focus on your task. Here we discuss several ways you can minimize "thinking."

Use Visual Elements Sparingly

Think of user interface controls and other visual elements as you think of clicks. Use them sparingly. Again, this might seem strange. What's one more menu or button or graphic? But just as clicks add up, so does visual clutter. The fewer things there are, the more easily you can find the one you need. Look at the two sets of "menus" in Figure 3.1. See how quickly you can find these items in each menu: Orange, Edinburgh, Cherry, and Gold.

Figure 3.1 Find the following items in Set A and Set B: Orange, Edinburgh, Cherry, and Gold. It's much easier to find them in Set B because there are fewer choices.

It was much easier to find the words in the second set than in the first, right? We made the task hard by choosing items that could have been in either of two or sometimes three categories in Set A. When searching for menu items in software, the situation is often worse because the categories are more arbitrary, so you may be able to rule out only one or two menus. The same principle holds true for buttons and other UI elements: Fewer items are better. Although scanning the screen doesn't take that much effort, once you start focusing on finding an item rather than doing a task, your flow is broken.

You might think that the more powerful your application is, the more widgets you need (buttons, menus, check boxes, and so on). Perhaps, but the fewer widgets you have for the same functionality, the more powerful your product. People can more easily find what they need, and since they can see what you're offering, they're more likely to use the functionality you worked so hard to provide.

Maybe you think we were exaggerating by showing such a strong contrast in the number of menus and menu items. Consider Figure 3.2. Out of the box, Microsoft Outlook 2000 Calendar has seven main menus, 69 menu items (16 of which are submenus), and 68 submenu items (not including your Web bookmarks, which are for some reason available in the Calendar), far more than our Set A has. Behind these 137 menu items are 42 pop-up windows, many of which launch yet more pop-ups. On the main screen are 12 task buttons across the top, access to six applications on the left, a column for folders, a view of today's appointments, an overview of this and next month, and a task pad.

Figure 3.2 Microsoft Outlook 2000 Calendar has far too many menus and user interface elements on its main screen, making it difficult to find the one thing you want.

In contrast, the Palm Date Book (shown in Figure 3.3) has three main menus with 18 menu items, no submenus, and 6 pop-up windows, fewer than our Set B. The main screen has three buttons at the bottom, two sets of choice boxes (lower left and upper right), and a view of today's appointments.

Figure 3.3 Palm's Date Book has a much simpler main screen that makes it easy to find what you want.

We have used both calendar applications, and although Microsoft's lets you do more things, we find Palm's far more effective. It's also less intimidating. You can find the things you most want to do quickly and carry them out easily, and even the things you do a little less often are easy to find.

Many Web sites struggle with this principle, especially on the home page. Everyone wants to have a link to the part of the site they're working on so that people are more likely to use their feature. The problem is that the more links there are, the less likely it is that people will find any one of them.

Once you start to think of every element on the screen as a scarce resource, you begin to feel cautious about adding features. Features almost always require extra visual elements. Even if you add just one more menu item, that item makes it harder to find the other items already in the menu. When you start to think about the UI cost of adding features (even ones that are easy to implement), you're beginning to think like a good interaction designer.

Design Guideline

Agonize over every visual element on the screen. The more there are, the fewer that get noticed. Make sure every visual element on the main screen is worthy of prime real estate. Even hidden elements must pull their weight because each one adds complexity.

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