Spatial Knowledge Navigation for the World Wide Web By William T. Neveitt B.S., M.Eng. Electrical Engineering and Computer Science (1996) Massachusetts Institute of Technology Submitted to the Department of Electrical Engineering and Computer Science in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Computer Science at the Massachusetts Institute of Technology September 2000 @2000 Massachusetts Institute of Technology All Rights Reserved Signature of Author:_________ Depaitment of Electrical Engineering and Computer Science September 7, 2000 Certified t Randall Davis Professor of Computer Science Thesis Supervisor Certified by: Whitman Richards Professor of Cognitive Science Thesis Reader Certified by: Seth Teller Professorof Computer Science Reader Accepted by: 4rthur C. 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Spatial Knowledge Navigation for the World Wide Web By William Neveitt Submitted to the Department of Electrical Engineering and Computer Science On September 7, 2000 in partial fulfillment of the Requirements for the Degree of Doctor of Philosophy in Electrical Engineering and Computer Science ABSTRACT Navigation is a fundamental but relatively underdeveloped method of information access. This thesis argues that a spatial metaphor can significantly enhance the navigability of a broad class of information spaces. Whereas previous efforts in information visualization have focused on increasing the amount of information available on the display, this thesis begins with the premise that there is far too much information to be seen all at once. To facilitate navigation, information architecture must help an end-user construct a working mental model of information that extends beyond the margins of the current view. I define the knowledge navigation problem and outline five specific criteria for its solution. I then survey the practice of hypertext design, identify several recurring navigation pathologies, and argue that these pathologies stem from a basic mismatch between the physical organization of a hypertext and a user's perception of it as viewed through a page-centered browser. As an alternative, I review a design framework based on elements from urban architecture including landmarks, regions, paths, direction, and proximity (LRPDP) and argue that these elements can improve the navigability of information architectures. To illustrate how the LRPDP elements can be applied in practice, I performed four case-studies: designing a citation database for machine vision, an on-line help system for software troubleshooting, a virtual dinosaur exhibit, and a digital research notebook for brainstorming. To evaluate the impact of a spatial view and of LRPDP design on navigability, I performed a series of usability studies. The results suggest that users explore more, remember more, and find more 2 answers to questions when provided with a spatial view of an information space. Further, subjects state their position more accurately, return to a known location more efficiently, and reorient more effectively when landmarks, regions, and paths are present. I distill lessons from the case studies and the usability experiments down to a collection of simple design principles for future information architects. Thesis Supervisor: Randall Davis Title: Professor of Computer Science 3 Table of Contents Spatial Knowledge Navigation for the World Wide Web...................................................... 1 Table of Contents .......................................................................................................................... 4 Acknowledgements........................................................................................................................6 Overview.....................................................................................................8 The Knowledge Navigation Problem.................................................................................... 10 IN TRO D U CTIO N .......................................................................................................................... 10 THE WEB REVOLUTION IS BEGINNING .................................................................................. 10 THE USABILITY DEFICIT IS A GROWING CHALLENGE ............................................................ 12 INFORMATION ARCHITECTURE CAN NARROW THE USABILITY DEFICIT .............................. 13 EFFECTIVE INFORMATION SPACES SUPPORT THE CREATION OF A MENTAL MODEL ................ 14 QUERY AND NAVIGATE ARE COMPLEMENTARY ACCESS PARADIGMS.................................. 15 THE KNOWLEDGE NAVIGATION PROBLEM................................................................................ 17 DIGEST OF PREVIOUS WORK ................................................................................................. 20 Navigation in Hvpertext ........................................................................................... ..... 22 O V ERV IEW ................................................................................................................................. 22 PERCEIVING THE WEB...............................................................................................................22 HYPERTEXT NAVIGATION PATHOLOGIES.............................................................................. 25 DIAGNOSING HYPERTEXT NAVIGATION................................................................................ 34 DIGEST OF PREVIOUS WORK ................................................................................................. 35 The Spatial Metaphor.................................................................................................................37 IN TROD U CTIO N .......................................................................................................................... 37 WHAT IS THE SPATIAL METAPHOR? ...................................... ......................... ................... 37 INSIDE THE SPATIAL METAPHOR ............................................................................................ 39 LRPDP: A COLLECTION OF SPATIAL DESIGN ELEMENTS..................................................... 42 Case-Studies in Information Architecture........................................................................... 46 IN TR ODU CTIO N .......................................................................................................................... 46 A SIMPLE 2D OVERHEAD PRESENTATION TECHNIQUE......................................................... 46 WHEN IS SPACE USEFUL 9................................................... .. .. ................................................ 47 EXPLORING THE EVOLUTION OF IDEAS IN THE MIT VISION SPACE ...................................... 49 TROUBLESHOOTING IN THE MICROSOFT OUTLOOK HELP SPACE.......................................... 52 LEARNING ABOUT DINOSAURS IN THE VIRTUAL DINOSAUR EXHIBIT .................................. 58 SENSE-MAKING IN THE THINKUBATOR .................................................................................. 60 4 CONCLUSION ............................................................................................................................. 67 Usability Studies in Spatial Navi ation ................................................................................ 68 INTRODUCTION .......................................................................................................................... 68 THE DIGITAL LIBRARIAN EXPERIMENT ................................................................................. 68 THE APERTURE EXPERIMENTS .............................................................................................. 91 EXPERIMENT 1: ESTIMATING CURRENT LOCATION .............................................................. 96 EXPERIMENT 2: RETURNING TO A LANDMARK ....................................................................... 100 EXPERIMENT 3: RE-ORIENTING............................................................................................... 103 LESSONS FROM THE A PERTURE EXPERIMENTS....................................................................... 104 Design Principles.......................................................................................................................108 Future W ork .............................................................................................................................. 112 Experim ent Instructions...........................................................................................................114 M aps From the Librarian Experim ent ................................................................................... 119 Biblio raphv..............................................................................................................................131