Postures for Other Platforms

Handheld devices, kiosks, and software-enabled appliances each have slightly different posture issues. Like Web interfaces, these other platforms typically express a tension between several postures. (For information on other design issues regarding these platforms, see Chapter 38.)

Kiosks

The large, full-screen nature of kiosks would appear to bias them towards sovereign posture, but there are several reasons why the situation is not quite that simple. First, users of kiosks are often first-time users (with the exception, perhaps, of ATM users), and are in most cases not daily users. Second, most people do not spend any significant amount of time in front of a kiosk: They perform a simple transaction or search, get what information they need, and then move on. Third, most kiosks employ either touchscreens or bezel buttons to the side of the display, and neither of these input mechanisms support the high data density you would expect of a sovereign application. Fourth, kiosk users are rarely comfortably seated in front of an optimally placed monitor, but are standing in a public place with bright ambient light and many distractions. These user behaviors and constraints should bias most kiosks towards transient posture, with simple navigation, large controls, and rich visuals to attract attention and hint at function.

Educational and entertainment kiosks vary somewhat from the strict transient posture required of more transactional kiosks. In this case, exploration of the kiosk environment is more important than the simple completion of single transactions or searches. In this case, more data density and more complex interactions and visual transitions can sometimes be introduced to positive effect, but the limitations of the input mechanisms need to be carefully respected, lest the user lose the ability to successfully navigate the interface.

Handheld devices

Designing for handheld devices is an exercise in hardware limitations: input mechanisms, screen size and resolution, and power consumption, to name a few. One of the most important insights that many designers have now realized with regard to handheld devices is that handhelds are often not standalone systems. They are, as in the case of personal information managers like Palm and Pocket PC devices, satellites of a desktop system, used more to view information than perform heavy input on their own. Although folding keyboards can be purchased for many handhelds, this, in essence, transforms them into desktop systems (with tiny screens). In the role of satellite devices, an auxiliary posture is appropriate for the most frequently used handheld applications—typical PIM, e-mail, and Web browsing applications, for example. Less frequently or more temporarily used handheld applications (like alarms) can adopt a more transient posture.

Cellular telephones are an interesting type of handheld device. Phones are not satellite devices; they are primary communication devices. However, from an interface posture standpoint, phones are really transient. You place a call as quickly as possible and then abandon the interface to your conversation. The best interface for a phone is arguably non-visual. Voice activation is perfect for placing a call; opening the flip lid on a phone is probably the most effective way of answering it (or again using voice activation for hands-free use). The more transient the phone's interface is, the better.

In the last couple of years, handheld data devices and handheld phones have been converging. These convergence devices run the risk of making phone operation too complex and data manipulation too difficult, but the latest breed of devices like the Handspring Treo has delivered a successful middle ground. In some ways, they have made the phone itself more usable by allowing the satellite nature of the device to aid in the input of information to the phone: Treos make use of desktop contact information to synchronize the device's phonebook, for example, thus removing the previously painful data entry step and reinforcing the transient posture of the phone functionality. It is important, when designing for these devices, to recognize the auxiliary nature of data functions and the transient nature of phone functions, using each to reinforce the utility of the other. (The data dialup should be minimally transient, whereas the data browsing should be auxiliary.)

Appliances

Most appliances have extremely simple displays and rely heavily on hardware buttons and dials to manipulate the state of the appliance. In some cases, however, major appliances (notably washers and dryers) will sport color LCD touch screens allowing rich output and direct input.

Appliance interfaces, like the phone interfaces mentioned in the previous section, should primarily be considered transient posture interfaces. Users of these interfaces will seldom be technology-savvy and should, therefore, be presented the most simple and straightforward interfaces possible. These users are also accustomed to hardware controls. Unless an unprecedented ease of use can be achieved with a touch screen, dials and buttons (with appropriate audible feedback, and visual feedback via a view-only display or even hardware lamps) may be a better choice. Many appliance makers make the mistake of putting dozens of new—and unwanted—features into their new, digital models. Instead of making it easier, that "simple" LCD touchscreen becomes a confusing array of unworkable controls.

Another reason for a transient stance in appliance interfaces is that users of appliances are trying to get something very specific done. Like the users of transactional kiosks, they are not interested in exploring the interface or getting additional information; they simply want to put the washer on normal cycle or cook their frozen dinners.

One aspect of appliance design demands a different posture: Status information indicating what cycle the washer is on or what the VCR is set to record should be provided as a daemonic icon, providing minimal status quietly in a corner. If more than minimal status is required, an auxiliary posture for this information then becomes appropriate.