The Information City - A Metaphor for Navigating Hypertexts

Recent research paper, presented at the BCS-HCI'93, Loughborough, England, Sept. 1993

Posted to alt.hypertext, sci.virtual-worlds and comp.human-factors in Oct.1993

Andreas Dieberger
outdated contact address kept on this page for consistency reasons!
Dept. for Design and Assessment of Technology
Vienna University of Technology
A-1040 Vienna, Moellwaldplatz 5/187
Tel: (+43-1) 504-11-86 Fax: (+43-1) 504-11-88
email: andreas.dieberger@acm.org

Jolanda G. Tromp
Faculty of Psychology
University of Amsterdam
Roeterstraat 15, 1018 WN Amsterdam
email: tromp@uvapsy.psy.uva.nl

Introduction

Hypertexts often suffer from the well-known phenomenon of "getting lost in hyperspace". As the user interface is one of the key components of a usable hypertext system, it is often seen as the key to this problem. Among the proposed solutions are graphical browsers to visualize the structure of the hypertext. However, graphical browsers soon become too complex and confusing to help. Solutions are fisheye views or adding more depth to the display of hypertext - leading to three-dimensional user interfaces [STAP93] and to virtual reality hypertext as suggested by Jay Bolter in his keynote lecture at the ECHT'92 [BOLT92].

Transferring hypertext to virtual reality cannot be achieved easily. A strong spatial interface metaphor is needed which supports orientation within and between hypertexts since it can help considerably in building and maintaining a cognitive map of the information space (see also [SHUM90]). The metaphor should support more than one user - leading to CSCW-hypertext environments [BERN93]. Examples of spatial metaphors for information systems are manifold [DIEB93a], the city metaphor being used frequently to illustrate navigational behaviour. Other examples are information farming [BERN93] or information landscapes [CHAL93].

Providing a three-dimensional version of the desktop alone does not help. Users often are unable to locate files since their desktops tend to be cluttered and objects are indistinguishable. Therefore a richer environment is needed that gives more information about objects. Document proxies are an example of a two-dimensional solution - icons which show not only the type of document but also give clues about the contents, size and so on. But there are far richer solutions possible.

Writing on the World and Knowledge in the World

An example of a non-immersive VR system to visualize information using spatial metaphors is the Information Visualizer [RoCM93]. It uses a strong spatial metaphor (the concept of rooms) but still presents not enough information about objects. Jay Bolter talked in his ECHT'92 keynote lecture about the concept of "writing on the world" to present more information to the traveller in spatial environments by "textualizing space". In real life traffic signs or floorplans in buildings are examples for writing on the world. Examples from earlier ages are the gable-stones in Amsterdam gracht-houses or wall paintings in egyptian graves. Donald Norman calls a similar concept "Knowledge in the world" [NORM88].

The enriched city metaphor is also a non-immersive virtual reality and makes use of "writing on the world" and "knowledge in the world" to convey more information to the user. In the city metaphor a house with open doors shows a document in strong relation to the topic looked for, a half-closed door signifies weak relation. The outside of the building also conveys information: about internal complexity and age of the document, about functionality and the like. A worn doormat shows a house that is entered very often and so on.

One of the main advantages of digitalisation is that digital documents don't change any more whereas typical real world artifacts like books look old after some time. In a public library book stains, marks, and dogears tell a lot about the usage of the book. Also the back of the book tells if it was read very often. New books will probably fall open at the last page read - old books tend to fall open at a page that has been read a lot (and probably contains important information). Such information is lost in a digital data. There are some systems that introduced aging of information into digital data: in [SALO90] it was tried to signify older documents using color, in [LBSS85] color was used to visualize change history in a text editor, and [HiHo92] describes edit wear and read wear in text-documents.

The Information City

Documents that grow older are a typical application of "Writing on the world". Given more information about documents it will be easier to distinguish between similar items and therefore it will be easier to navigate an information space containing such items. The information city is such an environment designed especially for navigation in hypertexts.

Hypertexts are represented as houses so that walking inside a house is navigation of the hypertext whereas travelling the city is navigation between hypertexts. The information city is restructured according to interest profiles given by the users and similarity of documents so that topics are grouped into 'districts of interest'. Walking along the street the user can look at related documents - like in a library where all books about a subject are on the same shelf.

Navigating longer distances by walking would be too slow - it could be realized using "teleporting" the user, but this could destroy any feeling of location. Instead a subway metaphor can be used. The subway delivers the user at important landmarks. In hypertext this solution is probably superior to flying (used in many virtual reality systems) because it is visually less complex (albeit boring) and doesn't therefore distract users too much from the information they are navigating. An additional surface navigation method, for instance a tramway, could be provided to allow quick scanning of districts [TOGN93].

The Information-City is a kind of actor. Open doors for instance are the typical way the actor communicates with the user. It never shows up but guides the user using a sort of picture language (landmarks, signs, light cues and the like). Such guiding cues are also typical for good real world architecture. A city should be lucid and easy to navigate [LYNC60], [AlIS77]. The actor should notice aimless wandering in the city (signifying that the user is probably lost) and place signposts or even temporal subway stations just in front of the user.

In its pure form the information city is a single user metaphor for reading hypertext only. Authoring for the information city poses some problems as houses normally are planned before they are built and hypertext with unconstrained linking structures cannot be visualized well as a house. It is therefore necessary to use a restricted set of visualisable buildings blocks for authoring. Those building blocks act as higher order abstractions for hypertext like higher order constructs do in a programming language. This strait-jacketing of authors [AnKa93] will be of utmost importance in a multi-author version of the Information-City to maintain user-interface consistency (see below). At the time of writing an external authoring tool based on building blocks is under construction [DIEB93b].

Collaborative Navigation in a MUD-based system

As an intermediate step to realization of the Information City a text-only version of the system is planned. Visual cues are translated into a texual description. This version looks similar to a text-adventure game. MUDs (Multi-User-Dungeons) originally were network based versions of text adventure games. In the past few years it turned out that MUDs - a sort of text-based virtual reality - could be used as powerful CSCW-environments [CURT92]. Many MUDs in the internet today act primarily as meeting places and not as games. Projects like MediaMOO try to build discussion fora inside MUDs - in those "places" even lectures can be held. Examples for advanced systems of this kind are the Astro-VR system, a MUD built for discussions among astronomers and the Jupiter system [CuNi93]. Those systems even use picture, sound, and video channels.

At the time of writing a MUD-version of the Information-City is in the planning state. While there is the disadvantage of text only representation this system will have a few advantages as it will be a multi-user system and authoring inside the city will be possible. Using this system we hope to gain valuable data about navigational behaviour, development of landmarks, and evolution of navigational paths through information space.

Since the MUD-version is a multi-user environment we expect users not to get lost in hyperspace that easy. A typical social action in MUDs is to help newcomers (so called "newbies") to find their way around - like helping tourists to find landmarks in a real city [CURT92] [BrRe93]. Preliminary results from a questionaire about navigational behaviour in MUDs proved that collaboration is a common strategy when being lost in a MUD [TROM93]. We expect users to develop collaborative browsing behaviour like in [MaOs93]. Results from the MUD-based version shall be used in the graphical version of the Information-City.

References

[AlIS77] Alexander C.: "A Pattern Language", Oxford University Press, 1977

[AnKa93] Andrews K., Kappe F.: "Strait-Jacketing Authors: User Interface Consistency in Large-Scale Hypermedia Systems", in: Frei, Schäuble: Proc. Hypermedia '93, Springer 1993, pp. 130-137

[BERN93] Bernstein M.: "Information Mining and Information Farming", lecture in Computers and the Humanities, Brown University, Providence RI, 1993

[BOLT92] Bolter J.D.: "Virtual Reality and the Future of Hypertext", keynote lecture at the European Conference of Hypertext, Milano, Dec. 1992

[BrRe93] Bruckman A., Resnick M.: "Virtual Professional Community: Results from the MediaMOO Project", presented at the Third International Conference on Cyberspace in Austin, Texas 1993

[CHAL93] Chalmers M.: "Using a Landscape Metaphor to represent a Corpus of Documents", to appear in Proc. Conference on Spatial Information Theory, Elba, September 1993, Springer 1993

[CURT92] Curtis P.: "Mudding: Social Phenomena in Text-Based Virtual Realities", FTP-able from parcftp.xerox.com in /pub/MOO/papers/DIAC92.*

[CuNi93] Curtis P., Nichols D.A.: "MUDs Grow Up: Social Virtual Reality in the Real World", FTP-able from parcftp.xerox.com in /pub/MOO/papers

[DIEB93a] Dieberger A.: "Summary Spatial Metaphors" posted to newsgroup alt.hypertext in May 1993

[DIEB93b] Dieberger A.: "The Information City - a Step towards Merging of Hypertext and Virtual Reality", Poster at Hypertext'93

[HiHo92] Hill W.C., Hollan J.D.: "Edit Wear and Read Wear", Proc. CHI'92, pp. 3-9

[LBSS85] Lippman A., Bender W., Salomon G., Saito M.: "Color Word Processing", IEEE Computer Graphics & Applications, June 1985, pp. 41-46

[LYNC60] Lynch K.: "The Image of the City", MIT Press & Harvard University Press, 1960

[MaOs93] Masinter L., Ostrom E.: "Collaborative Information retrieval: Gopher from MOO", Proc. INET'93

[NORM88] Norman D.A.: "The Psychology of Everyday Things", Basic Books, 1988

[RoCM93] Robertson G.G., Card S.K., Mackinlay J.D.: "Information Visualization Using 3D Interactive Animation", Comm. of the ACM, Vol.36, No.4, April 1993, pp. 57-71

[SALO90] Salomon G.: "New Uses for Color", in: Laurel B.: "The Art of Human Computer Interface Design", Addison Wesley 1990

[SHUM90] Shum S.: "Real and Virtual Spaces: Mapping from Spatial Cognition to Hypertext", Hypermedia Vol.2, No.2, 1990, pp. 133-158

[STAP93] Staples L.: "Representation in Virtual Space: Visual Convention in the Graphical User Interface", Proc. InterCHI'93, pp. 348-354

[TOGN93] Tognazzini B., personal communication, july 1993

[TROM93] Tromp J.G.: "An electronic inquery of perception among a mud-based community", results from a MUD questionaire, project memo posted to newsgroup comp.cog-eng, July 1993

last modified on 10/26/96

Andreas Dieberger
andreas.dieberger@acm.org