Balancing Awareness and Interruption in Mobile Patrol using Context-Aware Notification

Balancing Awareness and Interruption in Mobile Patrol using Context-Aware Notification

Jan Willem Streefkerk (Netherlands Organization for Applied Scientific Research (TNO), The Netherlands), D. Scott McCrickard (Virginia Tech, USA), Myra P. van Esch-Bussemakers (Netherlands Organization for Applied Scientific Research (TNO), The Netherlands) and Mark A. Neerincx (Delft University of Technology, The Netherlands)
Copyright: © 2012 |Pages: 27
DOI: 10.4018/jmhci.2012070101
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In mobile computing, a fundamental problem is maintaining awareness of the environment and of information presented as messages on a mobile device. In mobile police patrols, officers need to pay attention to their direct environment and stay informed of incidents elsewhere. To prevent unwanted interruption, a context-aware notification system adapts the timing and appearance of incident messages, based on user activity (available, in transit, or busy) and message priority (high, normal, or low). The authors evaluated the benefits and costs of adaptive notification compared to three uniform notification styles (presenting full messages, postponing messages or presenting indicators). Thirty-two trained student participants used a prototype notification system in a controlled mobile patrol task. The results were validated in a follow-up study with twenty-four police officers.
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In mobile professional domains, such as the police domain, increasingly more operational information becomes available. In addition, more and more interaction with mobile devices is required, straining users’ cognitive resources. Consider mobile police officers on foot patrol. They work in a dynamic environment characterized by large variations in time pressure and workload (Sørensen & Pica, 2005). They need to focus their attention on their direct environment to be able to detect criminal behavior. At the same time, they need to be informed about incidents occurring elsewhere which may require their presence. Thus, while on patrol, officers must divide their attention to ensure awareness of their direct environment and of incidents elsewhere.

Current notification systems in the police domain broadcast all incident messages to all officers as a central dispatcher does not know the current activity of each officer in detail. While this maintains officers’ awareness of incident messages, it can diminish awareness of the environment due to unwanted interruption. This causes officers to focus their attention inappropriately (e.g., on the device instead of on the environment) and can result in decision errors, longer response times and potentially dangerous situations. For example, a message about an illegally parked car (low priority) might be irrelevant and distracting for an officer who is just apprehending a suspect (high priority). However, to a high priority message about a colleague in danger, even officers engaged in an incident need to respond quickly. So, depending on two important context factors (message priority and officer activity), an incident message might constitute an unwanted or an appropriate interruption.

This illustrates a fundamental problem in mobile human-computer interaction: the cost-benefit trade-off that exists between awareness and interruption. Awareness of incident messages on a mobile device may be more important than the need to focus on the environment, requiring an interruption. On the other hand, avoiding interruption (e.g., by postponing messages) comes at the cost of delayed awareness of the message (Horvitz, Apacible, & Subramani, 2005; McCrickard & Chewar, 2003). Depending on the context (i.e., priority of the message), delayed awareness might not be a problem at all. Hence, to balance this awareness trade-off, notification systems should determine when a particular interruption is appropriate (appropriate timing) and how it should be presented (appropriate appearance) (Bailey & Konstan, 2006; McCrickard & Chewar, 2003; Streefkerk, van Esch-Bussemakers, & Neerincx, 2006). Previous research has shown that postponing, scheduling or deferring interruptions until appropriate moments mitigates the negative effects of these interruptions (Adamczyk & Bailey, 2004; Iqbal & Bailey, 2008; McFarlane, 2002). Also, the presentation modality (e.g., visually, auditorially) and salience of the message influences its interruptiveness (Kern & Schiele, 2003; Nagata, 2003; Streefkerk, van Esch-Bussemakers, & Neerincx, 2007).

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