Full interactive display
The third category of wearables in the Display On-Device factor is one that offers a full display. This allows for rich interaction with the device, which usually comes with a much broader feature set. Smartwatches and smartglasses are most common in this category, with an important distinction between them:
- ? Smartwatches have an actual physical screen on-device with which users interact.
- ? Smartglasses use a projected display that emulates a screen, but there is no actual physical one on-device.
Still, these devices share some key UX design challenges, mainly the small display size and mix of interaction patterns.
Small display size
Both smartwatches and smartglasses today offer a very small display area to present and interact with information and actions. For example, Samsung’s Galaxy Gear screen size is 1.6” with 320 x 320 pixel resolution; Sony’s SmartWatch offers a 1.6” screen, too, but with a resolution of 220 x 176 pixels. Google Glass offers a display resolution of 640 x 360 pixels, which is the equivalent of a 25” screen viewed from eight feet away.
From a UX perspective, this means the design needs to be very sharp — clear contrast, stripped down to the core essence of information — and to rely on large visual elements that are easy to scan and process at a glance. In that respect, surprisingly enough, the design principles for full display wearables share a lot more in common with designing for TV, compared to devices such as smartphones or tablets. Although TV screens are significantly larger, the information is consumed and interacted with from a distance, and thus require a simplified design, as demonstrated in Figure 4-24.
Figure 4-24. Comparison of interface design between TV and wearables: at the top is a TV dashboard by Comcast, followed by screen examples from Google Glass, and Samsung Galaxy Gear
In case the wearable display is not focused on information consumption only, but also allows touch interaction (as with smartwatches), the screen layout needs to accommodate the size of a human finger. Contrary to smartphones, for which interaction is often done using the thumb, when it comes to smartwatches, the index finger is the one most people use. The thumb is often needed to use physical keys on-device, or to help stabilize the device while using the index finger to press keys, as illustrated in Figure 4-25.
Figure 4-25. A comparison view between a common one-thumb operation interaction on a smartphone versus a
common smartwatch use
Looking ahead, comparing the two display types used by smartwatches and smartglasses today (physical screen and projected display, respectively), the latter seems to have better scaling prospects.[—] In fact, there are already several prototypes for smartglasses that offer a much bigger display area.[—] Still, when considering the display size, it’s important to keep in mind — especially with smartglasses — that bigger displays mean masking a bigger part of the visual field, as the displays are overlaid. We’ll discuss this more in the section Separate versus integrated visual field display.