Andreas Dieberger
Emory University
Multimedia Communications
550 Asbury Circle
Atlanta, GA 30322
andreas.dieberger@acm.org
Position paper for the CHI'97 workshop on Navigation in Information Spaces
Navigation, Social Navigation, Virtual Environments, Hypermedia, Web, Metaphors
When talking about navigation in information spaces we automatically use metaphors but we do not fully use these metaphors. Metaphors are incomplete mappings from a source to a target domain and thus carry certain restrictions. We should see these restrictions not as obstacles but as devices to communicate structure to our users. In the second part of this paper I talk about a new navigation behavior on the Web which is characterized by freely exchanging pointers to information in emails or other electronic media and using other people as information filters. I argue that we should try to better understand this behavior so we can better support it. From my own experiences it seems that spatial metaphors, for their social implications provide an excellent framework to support these social activities.
The start of my serious interest in navigation issues was Jay D. Bolter's keynote lecture at ECHT'92, the European Conference in Hypertext in Milan. After this lecture the idea of using an architectural metaphor for the navigation of large hypertextual information spaces (the "Information City") was born. Since then I moved away a little from the idea of the pure city metaphor and instead studied various aspects of spatial metaphors for information systems in more detail. Recently I re-discovered my older ideas as useful framework to support a new behavior we can observe on the Web: social navigation.
My current interest in navigation is mainly in two areas
I get the impression that we don't use metaphors to their full potential in navigation. They are not only vehicles to make something easier to understand, but -- especially in the case of information spaces -- they are also structuring devices.
Social navigation is a navigation behavior that is characterized by freely sending pointers to information to other people, providing reviewed lists of pointers, and so forth. It is not clear why people do share pointers and information so excessively on the Web, but it is a fact that they do and that this is an entirely new kind of navigation. We should try to better understand it to better support it.
Look at this section header - it is all so easy to say but what does that actually mean: "navigation"? What does it mean if we speak of an "information space"? What I sorely miss in the ongoing discussion of navigation in the Web or in any virtual environment is a detailed discussion of these issues.
The idea of the information space seems to be intuitively clear but is it really? Just speaking of a space triggers certain assumptions in us, because we are using a metaphor. Metaphors are mappings from a source domain to a target domain and they are necessarily incomplete mappings. Somewhere the analogy breaks down and this is exactly the point where metaphors in information spaces become interesting.
In a plain virtual environment there are no restrictions whatsoever and therefore no structure. By choosing a metaphor we impose a structure on the virtual environment. Structure is a necessary prerequisite for navigation. This structure then has to be communicated to the user. It has to be made visible -- or be "visualized".
Navigation is a mapping from the user's needs and a (visible) spatial structure to activities. These activities determine which tools to use to achieve a navigational goal. If a system "supports navigation" as is often claimed, this mapping must be supported in a way that users can easily choose the appropriate activity or tool to achieve their navigational goals. As an example consider using "flying" in a virtual environment. What does it mean if I use a "helicopter metaphor", an "airplane metaphor", a "balloon" or whatever. Each of these metaphors carries with it certain assumptions about the navigation possible and impossible with it. These limitations are not obstacles but provide opportunities to communicate structure or navigational constraints to the user.
When talking about navigation we therefore should be more aware of the underlying, implicit assumptions we are making. The restrictions metaphors impose on the information space are no absolute restrictions however -- it is well possible and sometimes even useful to break a metaphor and to introduce a magic feature (see Ref.1). A controlled break of the metaphor allows us to think of the space in terms of the metaphor and still to provide features that make using that space more efficient; after all that is what virtual space is all about: the possibility to improve on the limitations of real space we have to cope with all day. Stuffing a system with magic features eliminates the underlying metaphor however and the benefits of it are mostly lost.
One reason why I keep returning to a city metaphor in my work is its richness of sub-metaphors that can be used to provide structuring, navigation tools, access control, and social space. Most people are used to cope with city structures. People know how buildings work, how to find their way around in a city, what infrastructure to expect and how to use and give (even incomplete) route descriptions. The city is a collection of concepts that are very useful as source domains for structuring and navigation metaphors. For examples see Ref.4 and Ref.5.
The city is a very tempting metaphor and it is no surprise that a plethora of city-inspired systems are let loose on us on the Web. Unfortunately also in these systems the limitations of the city often have not been taken into account and so the city often is more a hindrance than a useful tool.
I don't think any more that creating a complete virtual city does make that much sense. However certain structures from the city are great source domains for metaphors. As an example look at buildings and rooms as containers. Just consider all the possibilities of using established protocols like having the door closed, slightly ajar, or open to signal access possibilities -- especially in multi-user systems. Reasonable use of city metaphors in this way is also a promising foundation to better support navigation involving groups of people: collaborative or social navigation.
On the Web an interesting phenomenon can be observed, especially in the past two years or so. When people find interesting Web pages they frequently copy their URLs into an email and send it to colleagues (recently this has changed a little and people tend the send the whole Web page as email -- maybe because the Internet finally is going to its knees). Similarly people invest a lot of time and effort into creating pointer pages to interesting stuff. These pages are a useful starting point when looking for specialized information on the Web: if I know a friend who is interested in a certain topic, then his pointer page is likely to be a gold-mine of relevant pointers. But that pointer page is even more: it is a reviewed, hand-selected list of pointers! When I check that page one could even describe this as using other people as intelligent agents (like Tom Erickson suggested) and everybody will agree that these are truly intelligent agents.
This free exchange of pointers and providing reviewed and filtered pointer lists is a very different navigation behavior from what we know from ordinary hypertext systems. I call this behavior social navigation (see Ref.3). In my opinion there is a strong trend to this sharing of pointers to information and therefore our systems should provide better support for it.
A few examples for the support of social navigation were realized in the Juggler (Ref.2) and the Vortex (Ref.3) systems, although both of these were not designed to be social navigation systems per se.
Juggler is a textual virtual environment that is coupled with a Web browser (see Ref.2). It provides bulletin boards showing read wear on their postings -- that is posting show if they are accessed a lot or not. The textual virtual environment also points out major navigation paths by highlighting exits that are used more often than others. But most importantly, Juggler provides a one-click point out a Web page to the person you are talking to feature which was excessively used by our users.
Social navigation is a new and large field. Besides directly pointing out information on the Web all systems that provide voting on the quality of pages, Web casting based on interest profiles, pointer lists, FAQs, etc. are facets of this behavior. From my experience with the Juggler system I believe that spatial metaphors, through their support of social space, are an excellent basis to support social navigation. We should try to better understand it so we can better support it in our systems.
2. Dieberger, A. (1996a). "Browsing the WWW by interacting with a textual virtual environment - A framework for experimenting with navigational metaphors". Proc. Hypertext'96. Washington DC: 170-179.
3. Dieberger, A. (1996b). "Providing Social Navigation for the World-Wide Web." International Journal of Human Computer Studies.
4. Dieberger, A., A.U. Frank (1997). "A City Metaphor to Support Navigation in Complex Information Spaces.
5. Dieberger, A. (1994). "Navigation in Textual Virtual Environments using a City Metaphor", PhD Thesis at the Vienna University of Technology, November 1994.