Make it Mobile

Design Challenges

A number of special considerations should be taken into account when designing information for small screens.

Small screen, loads of info

Most of the challenges related to designing for handheld devices stem from limitations of screen size. PDAs and cell phones are meant to be portable, so of course they are small. Therefore, small device, small screen. 

Jakob Nielsen, guru of Web usability, consistently states that users hate to scroll. He insists Web pages should be designed so users don’t have to scroll to see all the information. But avoiding scrolling on a PDA seems all but impossible if you want to present more than two or three sentences. News stories on the Web can take up 15 to 20 screens on a PDA. Scrolling on a PDA is unavoidable.

Another consideration is how to provide apparent navigation on a handheld device. Good Web navigation takes up a considerable amount of screen real estate. Nielsen states that a page should be made up of 80% content and 20% navigation. The Palm, currently the PDA with the smallest screen, has a display that measures a diminutive 160 by 160 pixels. Dedicating 20% to navigation seems to be quite a sacrifice of screen real estate. I would suggest dropping the navigation percentage to 10, or even 5.

Even as the screen space diminishes, the text must retain its legibility. As Kamba et al. point out, most users have a font size readability threshold of around 9 to 12 points. They go on to observe that as the screen shrinks, the font size remains the same and therefore takes up more space. Users are required to increase their interaction with the device (whether clicking or scrolling) in order to access the same amount of information.

Use the device, don’t fight it

But instead of tearing out our hair worrying about frustrated users, let’s celebrate this increased interactivity. After all, these are handheld devices. Owners of these devices are used to scrolling, pushing buttons, or using a stylus to enter text.

By examining some of the standard applications that are included on a device, you can determine the conventions of the interface and stick with them. Take, for example, the Palm’s icon of a house permanently printed onto the input screen at the bottom of the device’s display. It is always visible regardless of where you browse. Any time you click on this icon, it takes you to the main Palm OS menu. Information designers might want to take advantage of icons like this one.

AvantGo, the popular PDA browser, does just that. On every screen of content, a house icon sits in the upper right-hand corner of the page. Always present, this icon returns you to the main menu screen of the browser. Sticking with conventions such as these helps a user to develop a mental model of the way the information can be navigated.

Cellular phones, which are usually equipped with even smaller screens, also takes advantage of the device’s interface. Cell phones often have unlabeled, multifunctional buttons close to the screen. These buttons, instead of having one purpose, change depending on the information displayed on the screen above. For example, text may appear on the screen reading “Send,” indicating the button places a call. If a user is browsing on a cell phone, she would expect the same to hold true to select content. Instead of send, the prompt might read “next” or “back.”

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