Usability for Mobile Devices

Mobile Usability Testing

This is a user research column, so we definitely want to address how to do user research for mobile apps. Let’s discuss some factors you should take into account when doing usability testing next.

Considering the Context of Use

As we stated previously, it is extremely important to take into account the different contexts in which people use mobile apps. For this reason, it’s sometimes useful to incorporate environmental distractions into the context in which usability testing takes place. There are few ways of doing this. First, you can perform a field study in which a person attempts to use a device in a real-world environment like a coffee shop or other public place. This kind of approach maximizes external validity, which refers to the extent to which you can generalize the findings of a research study to the real world.

Another testing strategy is to simulate a real-world environment within a controlled area like a usability testing lab. This might include playing music or videos in the background or even inserting additional people into the testing environment to periodically initiate communication with a participant. All of this occurs as the participant simultaneously attempts to perform tasks on a mobile device. Finally, you can introduce distractions in the form of distracter tasks. Introducing a distracter task involves instructing a participant to stop what they are doing, perform a prescribed action, then return to what they were originally doing. An example might be: Whenever you hear the bell ring, stop what you are doing and write down what time it is in this notebook. While distracter tasks do not consist of meaningful actions and need not mimic real-world situations, they are relatively easy to incorporate in a test scenario and give you an idea of how distractions can impact a user’s interaction with your mobile app. If you’re able to do iterative usability testing, you can begin with more traditional usability testing, then introduce distraction elements further along in the testing process.

Capturing Data

Data collection can be a challenge when testing mobile devices. Because of mobile devices’ small size, it can be difficult to get a clear video recording of participants’ interactions with a device. This is particularly true for touchscreen devices, because when a participant interacts with a touchscreen, his or her hand also obscures the user interface. This can make is difficult to see what buttons a participant presses. Also, participants with large hands may obscure the user interface merely by holding a device in their hands. Finally, because mobile devices are usually handheld devices, people tend to move around quite a bit while interacting with them, rendering normal stationary cameras ineffective.

The easiest way to work around these issues is to do initial testing using functional mockups on a desktop or notebook computer. This can provide great initial guidance on your app’s interaction design, but it’s important not to rely entirely on this kind of testing. At some point during development, you should do usability testing on an actual mobile device.

When testing on mobile devices, there are several approaches we employ. To capture user interactions despite participants’ hands sometimes obscuring the screens of mobile devices, we like to use a screen capture utility that outputs a video stream. This lets us see what’s happening on a mobile device’s screen on a connected computer, on which we can save the video stream. To do this, you’ll need to find a screen recording utility for the platform for which you’re designing your app. Here are some screen capture utilities for a few popular platforms:

• Android—The Android SDK makes this possible. For a walkthrough of the process, read “How to Capture Screen on Android Phone.”
• iOS—This a little trickier. Most solutions require a jailbroken device. Veency from Cydia is great, because it allows wireless, live monitoring on your computer. Another option is Screenrecorder, also from Cydia.
• Blackberry—There are a couple of third-party apps that can accomplish screen recording on a Blackberry: BBScreenStream and Mobiola Screen Capture.

Although recording interactions lets us see what user interface elements participants use, it doesn’t tell us whether a participant might have hit a button by accident or show us the participant’s reaction. To capture that information, we like to focus a second camera on the device a participant is using. This helps us capture the way the device fits in the participant’s hands, accidental activations, mistakes in interactions, and any other issues involving the use of the device’s physical user interface.

Because mobile devices tend to move around as participants hold them, we sometimes assign someone to be a dedicated camera operator. In this way, we avoid asking participants to try to hold the device still or in an awkward position where it is visible to a camera, as well as mounting the device in a way that would not represent how participants would actually use the device. However, if having a dedicated camera operator is not a possibility, we ask participants to hold a device in a way that is comfortable for them and set up a stationary camera, zooming in on the device to a distance that ensures the device remains in frame, so long as participants’ movement remains within a reasonable range. Usually, we also set up a second stationary camera to capture participants’ facial expressions as they use an app. By combining these three data sources, we can capture just about any relevant information during a usability test.

Conclusion

The mobile space is an exciting new technology frontier. Eventually, it will probably come to be dominated by massive software companies and require substantial budgets to create apps that have a chance at success. But for the time being, independent developers and a new generation of startups have the opportunity to blaze a new path by creating innovative mobile apps that redefine the way people interact with mobile technology. To meet these ambitious objectives, designers and developers of mobile apps must understand a new set of usability constraints that are unique to the mobile domain, including the variability of the physical user interfaces for devices on a single platform, usage contexts that are rich in distractions and competition for users’ attention, and users’ sometimes engaging in simultaneous activities that require an app to maintain usability during single-handed operation.

Usability testing of mobile devices also presents some new challenges. Traditional, lab-based usability testing doesn’t adequately simulate the actual operational context of a mobile app. Collecting relevant data during a usability test session in which a participant is using a handheld device also requires some new approaches. Fortunately, tools exist to solve this data-capture challenge, and new tools are continually emerging as the smartphone market continues to grow.

This innovative mobile space has the potential to launch the next tech titan. Among the countless app developers who are now working in this space, the companies that rise to the top will necessarily have done much to overcome the new usability challenges mobile devices present.