Mobile usability testing presents its own unique challenges to data collection and observation. The screen size and design of the mobile hardware impacts how your participants are going to be viewing and interacting with your design. These challenges impact how recording devices and software are set-up for the usability sessions. In some set-ups, participants are given instructions to lay the mobile device flat on the table, or the device is placed in an unnatural stand for them to interact with. Although these provide a stable and reliable manner to record what the participant is selecting on the screen, they do not provide accurate or reliable data on hand gestures, postures or tap errors. The artificiality of the set-up also impacts participant satisfaction and perception of ease-of-use.
The three unique attributes to view in mobile usability testing are gestures, postures and tap errors:
1. Gestures
With touch screen devices, gestures provide insight on how participants understand the hierarchy of content. A ‘swipe’ gesture indicates that they believe that there is content on the same level (they are going to the next page) whereas a tap can indicate that they are going to a child page.
2. Postures
Postures provides insight into a wide range of usability issues. The participants posture can indicate their level of engagement with the application as well as legibility issues in the UI. If the mobile is brought closer to their face, then legibility is causing comprehension problems. Font size or difficult to understand icons are common examples of legibility issues. Hand and finger postures will provide insights into the level of confidence the participant has selecting within the UI. Switching hands during the session to move from using their thumb to interact with the UI to their index finger indicates that the user feels more reliable precision is required for the current task. This could be a cue that your tap area is too small.
3. Tap Errors
With touchscreens, selecting items with your finger rather than through a hardware button provides greater UI flexibility. With this flexibility brings greater room for design errors related to small tap areas. Sometimes referred to as ‘fat finger syndrome’. This is something that anyone with a touch screen device has experienced. As the level of experience and comfort increase with the touch screen device, tap errors tend to decrease. This problem varies from device to device depending on the screen calibration and personal settings.
When collected, these three attributes provide valuable insight to the true performance of the mobile design.
With these factors in mind, try to reduce these external factors by having participants use their own mobile devices during testing.
Gestures, postures and tap errors should be collected along with the other metrics of task success, satisfaction and ease of use. By noting and observing these 3 important areas, your mobile usability testing data and analysis will be more accurate, richer and more precise. Recommendations made will represent the whole mobile interaction experience resulting in a better mobile user experience.