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Vol.30 No.2, April 1998
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Graphical User Interfaces For Hierarchies

Workshop Summary

Louis C. Vroomen


Hierarchical classification is a basic cognitive model used in almost all fields and in all cultures. Hierarchies are used for information organization about libraries, computer directories, stock portfolios, demographics, and many more resources. Textual representations with nesting and indenting to show levels are popular, but novel graphical approaches with node-link diagrams, cone trees, hyperbolic trees, and treemaps are expanding the choices for designers and users. Some of the key issues for researchers and developers are:

Both the University of Maryland Human-Computer Interaction Laboratory (HCIL) and the Centre de Recherche Informatique de Montréal (CRIM) have been working on this topic for some time. In order to explore the current state of hierarchical representation, we organized a two-day workshop for researchers and advanced developers. We wished to ensure an open atmosphere with focused interaction, and therefore limited the range of topics and number of attendees.

We invited a few people we knew to be working in the field and a notice on CHI-ANNOUNCEMENTS generated many interesting additions (see program below). Over 20 people, from university, government and industry, participated in the workshop, with good representation from cognitive science, visualization and applications domains. The workshop had a modest international flavor with participants coming from Austria, England, Israel, Canada and the United States.


Steve Feiner provoked a continuing debate, with his opening speech, "Trick or Tree: The Role of Hierarchy in the User Interface". Deftly reminding the participants that hierarchies are not necessarily trees, the path was open for spirited discussions on this complex issue. Experts in cognitive sciences painted a portrait of the problem. Visualization experts presented potential solutions. And then these were reconsidered in the light of the experiences presented by the experts from industry.

Lively discussions ensued on topics such as metrics, taxonomies, mapping versus manipulation, and ontology.

Some of the main issues discussed were:

Many other points were brought up over the two days. Participants held spirited discussions during the catered lunches and continued through vigorous afternoon walks about the campus. The discussions, for many, continued in the evening, at a nearby restaurant. The good food, wine, beer and coffee helped us extend the collegial workshop atmosphere as we established new professional collaborations.

The workshop website provides information and links:

Program: Day 1

Opening Speech: Trick or Tree: The Role of Hierarchy in the User Interface
Steven K. Feiner,
Columbia University

Hierarchical Spatial Reasoning
Adrijana Car,
Technical University Vienna

Inclusive Selection Tasks in Hierarchies and Database Thesauri: Inherent Difficulties and Prospects for User Interface Designs
Mark Treglown,
University of Bristol

Navigation through Multimodal Hierarchical Spaces
Stephen Hirtle,
University of Pittsburgh

Treemaps for Novices: Improving comprehensibility by refining visual design
Ben Shneiderman,
University of Maryland

Keynote Address: VLSI for the Hyperbolic Tree (Very Large Scale Impact:-)!
Ramana Rao,
Inxight Software (by phone)

Benchmarking interactive systems: efforts at NIST and how they relate to visualization
Sharon Laskowski
The National Institute of Standards and Technology

Presenting Hierarchical Information in 3D Worlds
Michelle Zhou,
Columbia University

Visual elision: A technique to represent and explore complex hierarchies
Luc Beaudoin,
Centre de recherche informatique de Montréal

Day 2

GIZA: A framework for visualization
Louis Vroomen & Marc-Antoine Parent,
Centre de recherche informatique de Montréal ,

Animated Multiscale Interactive Treebrowsing
Kent Wittenburg,
GTE Laboratories

Containerization for hierarchies
Douglas Talbott

Interface Widgets for Manipulating Hierarchies
Catherine Plaisant & Ben Shneiderman,
University of Maryland ,

Lexicon Cruiser for Exploring Semantic Neighborhoods
Rich Mushlin,
IBM Research

Browsing Digital Libraries: A case study of the Library of Congress and WebTOC
Dave Nation,
Defense Department, Visiting Xerox PARC
Catherine Plaisant,
University of Maryland


Ben Shneiderman,

Catherine Plaisant,

Anne Rose,

Human-Computer Interaction Laboratory
University of Maryland
College Park, MD 20742 USA

Luc Beaudoin

Louis Vroomen

Marc-Antoine Parent

Human-Computer Interaction Group
Centre de Recherche Informatique de Montréal
Montréal, Qc, Canada, H3A 2N4

Additional Attendees

Nahum Gershon,
The MITRE Corp.

Kent L. Norman,
University of Maryland

David Rashty,
Hebrew University of Jerusalem

Barry Vaughan,
Johns Hopkins University

About the Author

Louis C. Vroomen is an advisor/consultant at the Centre de recherche informatique de Montréal (CRIM), in the Human Computer Interaction group. He has been working at CRIM since 1987 in speech understanding, user interface design and visualization of complex data.

Author's Address

Louis C. Vroomen
1801 McGill College, Suite 800
Montréal, Quebec
Canada H3A 2N4


Tel: +1-514- 840-1234

No earlier issue with same topic
Previous article
SIGCHI Bulletin
Vol.30 No.2, April 1998
Next article
No later issue with same topic