encouraged us to start with mobile web or apps as a way to focus on
optimizing key functionality and minimize ‘featuritis’. Such services usually
have overarching design guidelines spanning all platforms to ensure a degree
of consistency. The aim is usually on making the different interfaces feel like a
family, rather than on how devices work together as a system.
This works when each device is delivering broadly the same functionality.
Evernote, eBay and Dropbox (see figure 9.1) are typical examples: each offers
more or less the same features via a responsive website and smartphone apps.
The design is optimized for each device, but provides the same basic service
functionality (bar a few admin functions that may only be available on the
desktop).
Figure 9. 1 : Evernote offers broadly the same service functionality across
different device types
But this approach breaks down when the system involves very diverse devices
with different capabilities working in concert. In IoT, many devices do not
even have screens, or an on-device user interface. Multiple devices may have
UIs with very different forms or specialized functionality (see figure 9.2).
Even if the UI is only on one device, the service still depends on all the
devices working together in concert.
Figure 9. 2 : The Smart Things ecosystem contains a range of specialized
devices that complement each other.
It’s not possible to design a system like this by thinking about one device at a
time: this is likely to create a disjointed experience.
In order to use it effectively, the user has to form a coherent mental image of
the overall system. This includes its various parts, what each does and how
different objectives can be achieved using the system as a whole. Traditional
single-device usability doesn’t tell us very much about how to do this.