Can Adaptive Interfaces Improve the Usability of Mobile Applications

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Mobile applications are becoming increasingly widespread and complex. Many of these applications suffer from usability issues, including information overload, screen clutter, lack of task support and limited interaction mechanisms. Adaptive user
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    P. Forbrig, F. Paternó, and A. Mark-Pejtersen (Eds.): HCIS 2010, IFIP AICT 332, pp. 187–198, 2010. © IFIP International Federation for Information Processing 2010 Can Adaptive Interfaces Improve the Usability of Mobile Applications? Janet L. Wesson, Akash Singh, and Bradley van Tonder Department of Computing Sciences, Nelson Mandela Metropolitan University, PO Box 77000+2741 504 2323 {Janet.Wesson,Akash.Singh,Bradley.vanTonder} Abstract.  Mobile applications are becoming increasingly widespread and com-plex. Many of these applications suffer from usability issues, including infor-mation overload, screen clutter, lack of task support and limited interaction mechanisms. Adaptive user interfaces (AUIs) have been proposed to address some of these usability issues. The aim of this paper is to investigate how AUIs can improve the usability of mobile applications. This paper discusses several simple types of adaptation that have been shown to yield significant usability benefits for mobile applications. Two case studies are presented to illustrate how an AUI can be incorporated into different types of mobile applications. This paper also discusses the lessons learned from these case studies and pre-sents some implications for designing adaptive systems in the future. Keywords: Adaptive user interfaces, adaptive systems, mobile applications, us-ability evaluation. 1 Introduction Research has shown that modern information systems suffer from several usability problems (issues). These issues are mostly attributed to the complexity and lack of flexibility of the user interface (UI). Information systems developed for mobile phones also suffer from similar usability issues. The physical constraints of these devices have an impact on screen size and available interaction mechanisms. These constraints con-tribute to the existence of several usability issues for mobile applications. Adaptive User Interfaces (AUIs) can provide potential benefits for addressing these usability issues [1]. Adaptation of the UI has been identified as an important aspect to be considered in the design of modern information systems [2]. Adaptation techniques include adapting what information to present (information  adaptation), how to present this information (  presentation  adaptation) and how to interact with this information ( interface  adaptation). The aim of this paper is to investigate how AUIs can improve the usability of mo-bile applications. Several simple types of adaptation are discussed that have been shown to yield significant usability benefits for desktop systems and mobile applica-tions. Two case studies are presented to illustrate how an AUI can be incorporated into a typical mobile application and the benefits obtained.  188 J.L. Wesson, A. Singh, and B. van Tonder This paper is organized as follows. Section 2 discusses some usability studies high-lighting the usability issues associated with mobile applications. Section 3 discusses the benefits of AUIs and how AUI techniques can be used to address these problems. Sections 4 and 5 describe the design and evaluation of two case studies as well as the different forms of adaptation which were incorporated into these systems. Section 6 presents some lessons learned from these case studies and some implications for the design of adaptive systems in the future. 2 Usability of Mobile Applications The importance of mobile phones as a communication and computational device is increasing daily. The number of mobile phone users is increasing exponentially and the usability of mobile applications is becoming a critical factor [3]. Looije et al. [4] maintain that mobile devices currently suffer from a number of us-ability issues. These usability issues can be grouped into three main categories: •   Technical - which refers to the battery life of the phone, network connec-tivity and the limited screen size; •   Environmental - which refers to temperature, light conditions, noise, distrac-tion, mobility of the user, cognitive and psychological constraints for the user, competition for attention from other tasks and the need to manipulate objects other than the mobile device; and •   Social - which refers to usability issues relating to privacy, acceptance, adop-tion, comfort and personalization. A study on the usability of mobile systems conducted by the Nielsen Norman Group in 2009 in the United Kingdom and the United States showed that only 59% of all the required tasks were completed successfully. The usability issues identified in this study included [5]: •   Speed - the biggest factor contributing to users performing poorly. •   Screen - the screen size is too small. There is only a limited amount of in-formation that can fit on the screen. •   Typing – typing on mobile devices is hard. An example is logging in because passwords and usernames often contain a combination of digits and letters as well as special characters. The next section discusses how AUIs can be used to address some of the usability issues identified in this section, especially the limited screen size and interaction mechanisms. 3 Adaptive User Interfaces 3.1 Types of AUIs An adaptive user interfaces (AUIs) can be defined as: “…  a   software artifact that improves its ability to interact with a user by constructing a user model based on   Can Adaptive Interfaces Improve the Usability of Mobile Applications? 189  partial experience with that user.” [6] The basic premise behind AUIs is that users are different and therefore have different needs from an interactive system. The system should adapt to the user, rather than forcing the user to adapt to the system. Each user’s characteristics and/or past behaviour are modelled in an attempt to adapt to his/her needs and desires. AUIs can be classified according the input variables which influence adaptation and the types of adaptation effects. The following four variables commonly influence adaptation [4]: •   User:  User-based adaptation is commonly employed in AUIs. AUIs can adapt to the user’s preferences, knowledge and skills. •   Task: Adaptation according to the user’s current task can ensure that the ad-aptation is relevant and helps users in their current activity. •   System: Adaptation can take place to adjust to differing device capabilities and variables such as network connectivity (in the case of mobile devices). •   Context:  Adaptation according to the user’s current context can play an im-portant role, particularly in mobile applications. AUIs can adapt in many different ways in response to the above variables. Several AUIs have been implemented which adapt the UI to suit the individual user [7], pro-vide assistance with routine tasks [8], recommend and filter information based on user preferences and personalize the presentation of information [9]. Three broad classes of adaptation have been identified as suitable for mobile map-based applications [24]: •    Information:   The information selected and the organization of the information can be adapted. •   Visualization:  The presentation of information can be adapted. •   User Interface:  The user interface can be adapted in a variety of ways, includ-ing adaptation of the UI controls and the interaction techniques. 3.2 Benefits and Shortcomings Browne et al.  [10] identified a number of high-level potential benefits of AUIs, in-cluding improving accuracy and efficiency and aiding in user learning. AUIs have been touted as potential solutions for problems such as information overload and filtering, learning to use complex systems and automated task completion [11]. AUIs also provide the potential to deliver the benefits of customized software at a lower development cost per user [12]. AUIs can provide many potential benefits, but are not without problems. One of the fundamental usability principles identified by Nielsen [13] is user control and freedom. AUIs can be seen as taking control away from the user and putting them at the mercy of the system. Other possible problems and pitfalls include privacy issues, confusion, learnability and obtrusiveness [7, 14, 15]. Some adaptive systems try to make the adaptation process more transparent to users to aid their understanding and to help them develop a more accurate mental model of the system [16]. The following sections describe two case studies investigating the use of AUIs in the domain of mobile map-based applications. Mobile map-based applications were  190 J.L. Wesson, A. Singh, and B. van Tonder chosen as the application domain as these types of systems are widely used and suffer especially from limited screen size and static interfaces. These two case studies were chosen to investigate how an AUI could be incorporated into a mobile map-based application and the benefits obtained. In the first case study, an adaptive system was developed from scratch. In the second case study, an existing system was re-engineered to incorporate an AUI based on adaptation requirements identified in a field study.   4 Case Study: MediaMaps MediaMaps was developed as an example of an adaptive mobile map-based visualiza-tion (MMV) system. MediaMaps was only developed as an adaptive system and no non-adaptive system was developed, due to the nature of the functionality provided. MediaMaps supports three types of adaptation, namely information, visualization (presentation) and interface adaptation [17]. The design and evaluation of MediaMaps are discussed in the following sections. 4.1 Functional Requirements The functional requirements for MediaMaps were determined by looking at existing MMV systems and interviewing potential users. This process produced the following functional requirements: Capturing and location-tagging of photos, videos and sound recordings; organization of multimedia into collections, based on time and location; lap-based visualization of media collections and individual items; list-based browsing of media collections; searching of collections based on time and location; and saving and loading of views. Figure 1 shows a screenshot of MediaMaps, showing several media collections and items being visualized in a map-based view. Fig. 1.  Screenshot of MediaMaps showing different media collections   Can Adaptive Interfaces Improve the Usability of Mobile Applications? 191 4.2 Design MediaMaps was designed to adapt to the users, their tasks and their context. In order to learn user preferences, a logging mechanism was built into MediaMaps. User inter-action is recorded, and various algorithms are used to perform different types of adaptation. The different types of adaptation supported in MediaMaps are briefly discussed below. Information adaptation is implemented in MediaMaps by sorting media items into media collections based on time and location [18]. The Real-time Event Detection (RED) algorithm was extended to include different media items. The sorting of media items into collections helps to minimize the clutter problem that would otherwise result if a user’s entire media collection was visualized in a single view. The grouping of media items is based on time and location. Previous user behavior is used to model the user’s media capturing behavior. Media items captured at a similar time and at a similar location are grouped together to form a collection. Visualization adaptation is implemented in MediaMaps in terms of adapting the visualization to the user’s previous behaviour. One the most significant problems of standard zooming and panning techniques is that the user often needs to perform many operations to find information. To address this problem, the visualizations in MediaMaps are adapted in terms of the zoom-level, latitude, longitude, the time pe-riod and the current map style (road, satellite photograph or hybrid) [19]. An example of visualization adaptation is shown in Figure 2. The same media collection is shown before adaptation (left) and after adaptation (right). In this example, the zoom-level, map style and location have been adapted based on previous user behaviour. Fig. 2.  Visualization adaptation in MediaMaps, before adaptation (left) and after adaptation (right) Interface adaptation is implemented in the form of list ordering in MediaMaps. These lists include the list of media collections, list of cities and the list of saved views. An example of interface adaptation in MediaMaps is shown in Figure 3. The top section contains the adaptive section of the list, including the most recently used (MRU) option and the two most frequently used (MFU) options [20].
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