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  • Published: 2009

Usability considerations for mobile devices

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IMG_0482This was a paper for Randolph Bias’ usability class at University of Texas School of information.
It’s a very light look at mobile usability considerations in mobile contexts.

Recently, revolutionary devices such as Apple’s iPhone and the Palm Pre have illustrated how important usability is in creating distinction in an otherwise commoditized marketplace of mobile devices. Studies have shown that in terms of barriers to users’ acceptance of mobile computing applications, usability is second only to security (Casper & Gonsalves, 2005). The emerging consideration of mobile usability is a topic deserving focused attention.

Mobile usability diverges from other usability interaction research in a couple of important areas. In this whitepaper I will address the interactive limitations of small-form factor devices as well as the challenges posed in creating viable research methods for devices used in many different environmental and social contexts.

Form Factor – Using small devices

The scarcity of available space for input and output in small form-factor devices is a primary differentiator between mobile usability issues and those of standard desktop computing.

Exploring the usability constraints of small screens is a not a new topic. Early office devices, telephone systems, ATM’s, home appliance and entertainment equipment displays have all featured small displays in various forms for years. While these devices do not approach the interactive complexity inherent in modern mobile devices, earlier research findings still apply. Research has found that small screen displays have surprisingly little impact on readability, comprehensibility, or effective interactions (Duchnicky, Kolers, Dillon). Their findings conclude that small screens are best utilized to deliver brief and focused pieces of information and are very effective at doing so. Conversely, large amounts of information are difficult to convey using limited screen space. A tailored approach to presenting information on mobile devices is required. Simply squashing busy, large-screen interfaces to fit onto small screens – a too common experience in modern mobile web browsing – results in diminished usability. (Buchanan, Farrant).

Input methods for mobile devices have seen many iterations – moving from the stylus based “graffiti” inputs of early Palm PDA devices to the small external QWERTY keyboards on Blackberry phones to the breakthrough multi-touch gestural interfaces of the iPhone. The tactile feedback touchscreen in the Palm Pre offers a combination of multi touch screens with text input speed matching devices with dedicated keyboards (Hoggan 2008). In spite of rapid advancement, the continued iteration and expensive experimentation in these interfaces suggests that we have not yet arrived at a satisfactory solution to this problem.

Input speeds on mobile devices are still far slower and more cumbersome than the equivalent interactions on a desktop machine, yet so many applications do not take this issue into account when they repurpose desktop applications and sites for mobile consumption.

While these small device input/output issues can be constraining, there are several ways to work around them or use them to advantage.

1.  Create sites and applications that provide “direct, simple access to focused valuable content” (Buchanan, Farrant). Anticipate how users might need to access your content or services in mobile context and design a specific version of your services to accommodate those scenarios. Simply rehashing your existing user experience to fit the format of a mobile screen is not acceptable.

2. Simplify navigation, transactions and mental models. Screen real estate is precious and typical persistent navigation models found on modern websites may not be appropriate or possible in a mobile context. Scarcity of space limits the applications’ ability to display “knowledge in the world” and the user must compensate by keeping more task and navigation knowledge in their head. (Norman, Page 54). Because of these constraints it is best for mobile applications to focus on discrete tasks with minimal distraction and limited navigation options.

3. Apple has done an amazing job of creating a universal set of design and interaction patterns for the iPhone and most other mobile devices have as well. Use these conventions exhaustively.  Try to use recognizable icons and avoid verbosity wherever possible. Remove unnecessary words and try sticking to nouns and verbs that get the point across.

4. Evaluate all interactions that require text input from the user. If you can use alternative input methods like select boxes or radios you should do so. (Buchanan, Farrant)

5. Properly constructed native apps are more usable than mobile browser based versions of the same experience (Caspar, Ryan). The recent mass adoption of the Webkit standard for mobile browsing is weakening this divide but for now native apps provide optimal user experience.

Research Methods for mobile usability in context

Traditional usability research methods are being used successfully to study interactions with mobile devices but there is a deficiency in these toolsets when it comes to measuring and analyzing the specific challenges of mobile contexts. Mobile devices, by definition, are not bound to controlled environments like home or office workspaces. As a result, the traditional methods of observation, note-taking and videotaping research subjects, pose issues when you try to apply them to mobile user testing. Furthermore, a lack of mature, installable usability measurement software hampers standardized collection of quantitative usability data currently available in the desktop computing space.

Penny Hagen proposes new research approaches to compensate for these challenges through the use of “Mediated Data Collection” and also “Simulations and Enactments” (2005) as enhancements to traditional usability testing practices.

“Mediated Data Collection” can be accomplished by having users do self-reporting via diaries or routine ‘check in’ surveys, log analysis, and wearable personal recording devices like sensors or cameras. Through these methods the researcher can make empirical observations about real world mobile device usage with the least impact on the interactions themselves.

In Inseong Lee’s 2005 longitudinal usability study we get to see some of these methods in action. He was able to use a combination of phone-based questionnaires and mobile data logs from subjects’ service providers to survey environmental and social contexts mobile data users in relation to what services they used at any given time, a deft use of Hagen’s mediated data collection techniques.

Hagen’s “Simulations” technique allow researchers to conduct traditional observation but reproduce certain environmental circumstances in a laboratory setting by using props, prerecorded ambient noise and actors. “Enactments” help to set up a social context through role-playing and storyboarding to reproduce social situations.  These would be helpful for creating scenarios such as “You are in a train station with high levels of ambient noise” accompanied by actual ambient noise played through speakers in the usability lab. You could further try to impart situational factors by crafting an enactment story such as “You’ve missed your train. Please use this mobile device to find the current train schedule.”


The small form factor of mobile devices, and the difficulty of studying the real contexts in which they are used, creates unique usability problems. The growing ubiquity of these devices and services that support them will undoubtedly generate much new research focused on improving user experiences and nurturing efficiency, effectiveness and satisfaction (Coursaris, Kim, 2005).

It’s difficult to do a literature review on a topic as broad as mobile usability. The amount and variation of research available is literally overwhelming and I feel like I’ve just scratched the surface. Hopefully I’ve captured a few of the most interesting and relevant issues and glued them together into a sensible introductory narrative.


Caspar, Ryan, Gonsalves, Atish (2005) The Effect of Context and Application Type on Mobile Usability: An Empirical Study

Proceedings of the Twenty-eighth Australasian conference on Computer Science – Volume 38


Coursaris, C. K. & Kim, D. J. (2006). A Qualitative Review of Empirical Mobile Usability Studies. Proceedings of the Twelfth Americas Conference on Information Systems, Acapulco, Mexico August 04th-06th 2006,


Duchnicky, R L & Kolers, P A (1983)

Readability of text scrolled on visual display terminals as a function of window size

Human Factors, 25:683–692


Hoggan, Eve, Brewster, Stephen A.  and Johnston, Jody (2008)

Investigating the Effectiveness of Tactile Feedback for Mobile Touchscreens

Glasgow Interactive Systems Group, Department of Computing Science



Author(s): Hagen Penny,  Robertson Toni


Proceedings of OZCHI 2005, Canberra, Australia.  November 23 – 25, 2005.


Lee, Inseong, Kim, Jaesoo, Kim, Jinwoo (2005)

Use Contexts for the mobile internet: A Longitudinal Study Monitoring Actual Use of Mobile Internet Services

International Journal of Human-Computer Interaction


Norman, Donald A. (2002)

The Design of Everyday Things.

New York: Basic Books.

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