Based on our experience accumulated in designing interfaces to support Exploratory Browsing, we have identified several general issues which should be considered in designing interfaces for media collection. Specifically we categorize them into five categories (see Figure 11.4).
Prototype Characteristic Photo Sim Music Sim Cloud Monster Photo Magnets His Flocks Tag Clusters SARA Music Trends Using different data sources
Original metadata √ √ √ √ √ √ √ √ System-generated data √ √ √ √ √ User-generated data √ √ √ √ √ √ Flexibility Multiple representations √ √ √ √ √ User interaction √ √ √ √ √ √ √ √ Personalization √ √ √ √ √ √ √ Understandability √ √ √ √ √ √ √ √ Reproducibility √ √ √ √ √ √ √ √ Scalability √ √ √ √
Figure 11.4: General suggestions for designing interfaces for media collections.
Using Different Data Sources
Data with different forms and origins can be combined to enrich the browsing possibilities. Normally the most reliable information comes from the item‟s original metadata, such as captured time of photos and music‟s ID3tags of artist and album. Users often use these fundamental and reliable criteria as the main principles for organization and browsing, therefore we introduce them in all prototypes. Besides these commonly used reliable criteria, additional options are also appreciated, which can be achieved by utilizing the system‟s and users‟ contributions. Additional information can be obtained through an analysis of the raw data, such as events extracted from photos‟ time stamps in PhotoMagnets, and hierarchical tag structure built on a text analysis in TagClusters. Using content analysis, additional features
besides similarity can be read out, such as background color and light status in photos, and gender, genre and mood for music. They can be used to create additional views for the entire collection, to conduct example-based search, or to generate content-based suggestions. Although this kind of system-generated data is less reliable, it complements the browsing possibilities offered by commonly used reliable criteria. User-Generated Data (UGD) is another source of additional information, which is extensively used in our prototypes. Data generated by single users conveys semantic relatedness of items on a personal level. When large numbers of users are involved, this information becomes more general and reliable in a broader range. We categorize this collaborative UGD as implicit and explicit UGD. Implicit UGD includes data recorded implicitly through user interactions, such as consumption histories, which reflects the users‟ personal tastes and consumption patterns. Explicit UGD is contributed by users on purpose, such as tags, ratings and reviews, which conveys the users‟ opinions and experience in detail. Since the size of a collaborative UGD collection is normally quite large, an aggregation is necessary to reduce the data complexity. Our exploration in Part II and III confirmed the effectiveness of UGD to encourage discovering new items, deriving additional insights and acquire knowledge which cannot be easily obtained through a linear scan of respective collections.
Flexibility
People‟s activities around media collections are highly dynamic and often unstructured (cf. Chapter 2). To support the behavioral dynamics, the interface should allow a high degree of flexibility, which we believe can be introduced in three ways: As users‟ mental model of their collections often goes beyond a fixed linear structure, multiple representations allow them to look at the collections in different ways, thus enhance the browsing flexibility (more details see “General Purpose Browsing” in Section 11.3.2). Moreover, different criteria can be combined
in one representation to offer more browsing possibilities. An efficient combination with traditional interface elements can accelerate the users‟ acquaintance with novel concepts. For example, we combined the magnet metaphor with the conventional tree view in PhotoMagnets, and the results of the user study confirmed a high degree of interface appropriation. Users may frequently switch back and forth between different views, therefore, they should be closely coordinated and smooth transitions between them should be ensured.
User interaction can help users to make more sense of the underlying system logic. Options to override the results of automation can enhance the degree of personalization, and thus improve the users‟ feeling of control and enjoyment. Especially in a large-scale collection, personalization is essential to support an efficient browsing based on personal preferences and interests. Better motivated users may spontaneously discovery new features of the system which are not foreseen in the original design, such as the advanced usages of magnets in
PhotoMagnets. For systems built based on content analysis, there is always a semantic gap between low-level features and high-level perception. In this case, users‟ adjustment offers an opportunity to correct the system‟s inappropriate interpretations. The simplest way of user manipulation is to allow making changes manually, for example, repositioning items by drag-and-drop. As the size of current collections is always in steep growth, manual adjustment
11.3 Summary of the Results 159
may be tedious and time-consuming. Therefore, it seems more appropriate to offer semi-automatic solutions which efficiently combine the system‟s intelligence and the users‟ feedback: Users select several key points and the system conduct the corresponding adjustment. For example, in PhotoSim and MusicSim, the user can adjust the number of clusters, and accordingly the system will re-cluster items to produce a new layout. Similarly, in the global recommendation mode in SARA, the user can replace any sight in a plan and the system will automatically update the subsequent part of this plan. Adjustable representation not only facilitates personalization, but also creates a chance for backtracking. For example, it is possible to recovery from an operation mistake or switch back to a previous status by resetting the corresponding parameters. To improve the directedness and continuity of the traditional turn-taking interactions and offer users a seamless exploratory experience, a synchronous feedback should be tightly coupled with the users‟ manipulation. Dynamic Query (Ahlberg and Shneiderman, 1994a) is a simple and efficient solution, with which users can observe an immediate change with their actions, for example dragging a magnet or a slider.
Understandability
Understandability is a general requirement for user interfaces. To illustrate the system logic, for example how a representation is organized or why certain items are recommended, additional information can be integrated in the item rendering to enhance the understandability. In general, size and color are the most commonly used attributes. Size can represent the popularity of an item, and color can be used to distinguish different categories, or to describe the similarity between items.
The location information can reflect the semantic or geographic relations between items, thus make the item positioning understandable and meaningful. Specific concern should be paid to a placement based on overall similarity, which is in some cases arbitrary and unintuitive. We suggest applying similarity in local levels to achieve a more accurate performance, or combine it with other more reliable criteria to offer a clearer explanation of the organization.
Reproducibility
Good reproducibility is essential to maintain the representation consistency. Map-based systems bear good reproducibility with precise geographic location information. Force-directed layout is widely used to automatically group similar items based on their overall similarity. However, this placement is rather arbitrary, due to the randomness of the underlying force simulation mechanism. When the application re-launches, an exact same visualization cannot be promising. This problem can be solved by automatically saving the position of each item. A more precise positioning method beyond the overall similarity should be included to enhance the system reproducibility.
The reproducibility in one usage session can be improved by automatically or manually saving the current status, which enables switching back to a previous status. A same effect can also be achieved by adjusting relevant parameters.
Scalability
The system‟s scalability is important towards realistic collection sizes. Although map-based interfaces bear good reproducibility with the precise location values, scalability is a crucial issue, especially when many items share similar locations. For systems built based on overall similarity, an overlapping detection mechanism can efficiently solve the problem of occlusion by placing overlapped items further away from each other. It should be combined with a tightly coupling method to avoid possibly large wasted space. Grouping similar items and expanding them on demand can be a general compensation for scalability.
Based on the five criteria discussed above, we analyzed our prototypes accordingly (see Figure 11.4). All prototypes used at least two categories of data sources. More than half of them provide multiple representations. All of them preserve users active control, and allows them actively steering the system and thus creating personalized representations. Items in each system are encoded with additional information. Reproducibility in one usage session is ensured by saving the current status. Due to the randomness of force-directed layout, the exact same layout for two subsequent applications cannot be promising, and our current solution is to save the item locations automatically. Admittedly, a more precise positioning method is necessary. Occlusion problem is solved by an overlapping detection method, but the rather loose representation needs further optimization, and a tight coupling mechanism can make better usage of the space. Considering the limited space between items, such as sights on the
SARA map, or magnets in CloudMonster and PhotoMagnets, a semantic grouping can alleviate the problem of occlusion.
12
Future Work
Building upon our experience accumulated in this research, we identify several aspects of interest for improvement and future work. The prototypes presented in this thesis can be improved with additional refinement. In this chapter, we focus more on the aspects of interest for our future research as well as issues worth consideration for the area of interface design to support exploratory experience.
12.1
The Model of Exploratory Browsing
Our exploration in this thesis helps deepening the understanding of how people‟s behavior and requirements have an influence on the design decisions. We have proposed a new model of
Exploratory Browsing to inform the interface design to support the Exploratory Browsing
experience with media collections. Our studies yield promising reflections on the refinement of the model, which brings substantial insights for designing browsing interfaces for media collections. This model needs more extensive investigation, especially with the stimulators to ensure a smooth transition between different browsing activities.
One direction in our future work is to elaborate the current model of Exploratory Browsing
to guide the design of new interfaces for media collections. In this thesis we have explored two main usage contexts: browsing with personal collections and in online communities. To improve the generality of our model, co-located environment needs investigation, which differs from the other two usage contexts in the social aspect. It would be interesting to observe people‟s behavior in a co-presented environment, and to examine how their exploratory activities would differ from those in the other two usage cases. We expect that such an exploration can bring substantial insights to generalize the model of Exploratory Browsing by covering broader usage contexts.
Another aspect worth consideration is the evaluation methodology. Evaluating exploratory interfaces is difficult, and the main challenge is to find ways to evaluate the system‟s effectiveness to support the user‟s exploratory experience. To understand the user behavior and how it has impact on the interface design, we have applied different evaluation approaches, according to the different characteristics of our prototypes (cf. Figure 11.1 in Chapter 11), for example, empirical evaluation and explorative study, comparative study and insight-based evaluation. The experimental studies reported in this thesis were conducted in a laboratory environment. Long-term studies can provide more in-depth comprehension of system usability (Shneiderman and Plaisant, 2006). Also, deploying real tasks rather than synthetic ones can encourage the users‟ engagement (Saraiya et al., 2005). We expect that such exploratory and long-term studies could be more informative and bring more values to examine whether the users‟ practical browsing activities can be efficiently supported and how they inform possible refinement of the current model of Exploratory Browsing.
Through such investigation and experimentation, we expect to propose a more elaborate model of Exploratory Browsing. All in all, we hope that our work can shed some light on the interface design by informing the model of Exploratory Browsing and corresponding general guidelines to support the exploratory experience with media collections.