The evaluation of mobile applications is increasingly taking into account the users of such applications’ mobility (e.g., Mizobuchi, Chignell, & Newton, 2005; Mustonen , Olkkonen, & Hakkinen, 2004). While clearly an important factor, mobility on its own often does not require the user’s visual focus to any great extent. Real-life users, however, are required to be aware of potential hazards while moving through their environment. This chapter outlines a simple classification for describing these distractions and two evaluations into the effect visual distractions have on the users of a mobile application. In both cases, the participants were required to monitor both their environment and the display of their mobile device. The results of both evaluations indicated that monitoring the environment has an effect on both task performance and the subjective workload experienced by the participants, indicating that such distractions should be considered when designing future evaluations.
Key Terms in this Chapter
Lab Evaluations: The evaluation of a mobile application that takes place in a laboratory. The advantages of such evaluations include ease of controlling the environment and data capture. Disadvantages include difficulties in creating an appropriately realistic evaluation setting.
Interfering Distraction: A distraction that interferes with a user’s ability to interact with their mobile device. Such distractions may be passive or active. Examples of such distractions include traffic noise interfering with a mobile device’s audio feedback or oncoming pedestrians that limit a user’s ability to monitor the visual display of a mobile device.
Field Studies: The evaluation of a mobile application that takes place in the actual context of use. The advantage of such evaluations is that problems that only arise in the particular context will be detected. The disadvantages of such evaluations include difficulties in controlling the environment and capturing evaluation data.
Wearable Computer: A mobile computing device that the user wears rather than carries. The processing unit may be worn in a pouch on a belt or in a bag. Various interaction devices may be secreted around the user’s body including: a handheld input device such as a trackball, a wrist mounted keyboard, or a head-mounted display. The advantages of such devices over handheld mobile devices include: faster access to the device, increased privacy, and hands-free access to data.
Earcon: Abstract, structured sounds used to provide information to a user. The musical qualities of the sound (e.g., rhythm, timbre, or pitch) can be varied to convey information to users. Earcons can be combined sequentially (compound earcons) or concurrently (parallel earcons).
Active Distraction: A distraction that a user must respond to in some way. Examples of such distractions include hazards that a user must avoid (e.g., a lamp-post) or a mobile-phone that the user answers when it rings.
Head-Mounted Display: A display that allows a user to view the visual output of a wearable computer at all times. Such displays may cover one eye (monocular) or two (binocular). They may be opaque (for immersive environments) or transparent (allowing the user to simultaneously view the surrounding environment). The displays may attach to a pair of glasses (glasses-mounted display) or be attached to a form of headwear such as a hat or band.
Passive Distraction: A distraction that may “put-off” the user but can be ignored. Examples of such distractions include billboards mounted on the side of buildings or the sound of traffic on a distant road.