Mobile apps – Some usability guidelines
Mobile apps should clearly prioritise key content and provide a ‘Back’ button if the device does not. Mobile apps should also minimise users’ data entry and ensure a consistent user experience across different mobile device orientations.
Introduction – mobile app usability
According to recent data, approximately 56% of the UK population have an active mobile-broadband subscription . This means that designing for mobile devices has become a critical usability issue for most organisations. Whilst the usability guidelines for designing for mobile devices are still evolving (based on the audience’s developing familiarity with – and our usability knowledge of – the medium), there are some basic guidelines which appear reasonably robust.
These guidelines have been derived from our experience of conducting user research, usability testing and user-centred design projects for mobile devices (both for mobile sites and also mobile apps). We suggest that these guidelines may help usability professionals to design usable and useful mobile apps.
Prioritisation in mobile app design
The best mobile apps that we have encountered almost always try to present users with a simplified view of an organisation’s content and/or functionality. This usability guideline can be understood to directly relate to two of the main defining characteristics of mobile devices:
- Small screen sizes: Mobile devices have less screen space than desktops and laptops. This means that perusing large amounts of information can be awkward and inconvenient.
- Users’ attention is limited: Most mobile devices are currently used while the user is ‘on the go’ or multi-tasking in some form (such as watching TV or sitting in a business meeting, for example). This means that the average mobile app user will have a very limited amount of attention to expend on that mobile app.
These usability considerations mean that we would recommend that mobile apps – as far as possible – have a very specific focus and only offer a limited set of content and functionality (especially when compared to an organisation’s full website). Of course, this can be a very challenging facet of mobile app design and may require an organisation to make hard choices about what content and functionality its audience should be able to access through a mobile app.
Irrespective of the overall focus of the mobile app, however, it is also the case that the importance of prioritisation continues within the mobile app itself. In our experience of usability testing mobile apps, mobile apps work best when they focus on a single main piece of content or functionality at any one time. This allows the mobile app’s design to be clearly focused on the presentation and communication of its primary ‘goal’ at that point.
Provide ‘Back’ buttons for mobile app usability
Mobile apps represent self-contained environments that allow designers a great deal of freedom with – and control over – the user experience. This aspect of mobile apps represents a great opportunity for usability professionals, but it also requires designers to accept certain usability responsibilities.
One of the most important of these usability responsibilities is for the mobile app to explicitly provide any user support which might otherwise have been provided by the mobile browser. In our experience of mobile app usability testing, the main piece of browser-support which users want replicated within mobile apps is the ‘Back’ button. Note: this usability recommendation does not apply to mobile devices whose handsets have a dedicated ‘Back’ button (such as Android mobile devices, for example).
We recommend that mobile app designers strongly consider incorporating an explicit ‘Back’ button within their mobile app designs. This becomes even more important if the mobile app includes a process which the user is expected to complete. Our usability testing has shown that the inclusion of this feature (particularly for process-relevant screens) is a key usability issue for mobile app design.
Minimise data input to improve mobile app usability
Mobile app designs should generally require the minimum possible data input from users. The main usability reasons for this are that data entry is – on most mobile devices – not very easy and requires significant time and attention. As discussed above, some of the main defining characteristics of mobile devices mean that mobile apps are likely to be used within contexts where users’ time and attention will be in limited supply.
As such, mobile apps should always try to minimise the amount of data entry required of their users. A useful way to potentially reduce the amount of data entry required of users can be to allow users to make a selection from a predetermined list, rather than have to enter data. Techniques such as this can help improve the usability of a mobile app design.
Managing orientation changes within mobile apps
Most users expect a mobile app to respond to a mobile device’s orientation change (for example, from portrait to landscape) with an appropriate change in layout. Ensuring that mobile app designs behave in this way has the benefit of not only meeting users’ expectations (which is an important usability principle in itself), but also allowing a mobile app to present content in an orientation-optimised layout.
Mobile app designers should, however, take care to support a consistent user experience across a mobile app’s different orientation-optimised layouts. As part of this, it is an important usability consideration that a mobile app’s focus and interface be made as consistent as possible across different mobile device orientations. In our mobile app usability testing sessions, we have found that CTA (Call To Action) placement, appearance and information-formatting are particularly important to the usability of mobile apps’ responses to mobile device orientation.
Summary – some usability guidelines for mobile apps
Mobile apps design guidelines are still evolving, but our usability testing sessions have suggested some useful basic guidelines. These include that a mobile app should only focus on key content/functionality and each of its screens should have a clear priority.
We also recommend that mobile app designers consider introducing clear and explicit ‘Back’ buttons (especially on process-related screens) where the mobile device does not have a native equivalent. Other usability guidelines include mobile apps minimising users’ data entry wherever possible and ensuring a consistent user experience across different mobile device orientations.
 ICT Facts and figures 2011
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