THE STUDY AND DESIGN OF ALGORITHM ANIMATIONS by ASHLEY GEORGE HAMILTON-TAYLOR (Under the Direction of Eileen Kraemer) ABSTRACT Algorithm Animations (AAs) portray the high-level dynamic operation of an algorithm. The computer science education community held great expectations that AA would assist students in understanding algorithms. However, many studies of the instructional effectiveness of AAs have produced inconclusive results. We investigated a number of issues pertinent to AA effectiveness: the study of AA user needs, user-centered design and the role of perception in AA. Existing algorithm animation systems typically have been designed without formal study of related teaching practices. We conducted an observational study of instructors teaching data structure and algorithm topics, focusing on activities involving the use of diagrams and algorithms. The results of this study were used to inform the user-centered design of SKA, the Support Kit for Animation. SKA combines interactive data structure diagram manipulation with flexible pseudocode execution, simple algorithm animation authoring support, a visual data structure library, and an animation engine designed for perceptual pacing and timing. The role of perception in AAs had not been formally considered in the past. We collaborated on a number of empirical studies to investigate this role, and the design of software to be used to conduct these studies. We found that some animation techniques can assist user perception and mapping in AA in some contexts, which will inform future AA design and studies. INDEX WORDS: Algorithm Animation, Software Visualization, Algorithm Visualization, Program Visualization, Human-Computer Interaction, Educational Technology, Perceptual Study, Perception, Perceptual Processing, Empirical Study, Observational Study, Usability, User Interface Design THE STUDY AND DESIGN OF ALGORITHM ANIMATIONS by ASHLEY GEORGE HAMILTON-TAYLOR B.Sc., University of the West Indies, Mona, Jamaica, 1985 M.S., University of Illinois Urbana-Champaign, 1991 A Dissertation Submitted to the Graduate Faculty of The University of Georgia in Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY ATHENS, GEORGIA 2006 © 2006 Ashley George Hamilton-Taylor All Rights Reserved THE STUDY AND DESIGN OF ALGORITHM ANIMATIONS by ASHLEY GEORGE HAMILTON-TAYLOR Major Professor: Eileen Kraemer Committee: Robert Branch Elizabeth Davis Maria Hybinette Electronic Version Approved: Maureen Grasso Dean of the Graduate School The University of Georgia August 2006 DEDICATION As I prepared this, I sat by the waters of the King Center, and a thought came to me: perhaps life is as much about what we learn on the journey as what we achieve. May there be peace on this earth for all its inhabitants, and especially for all my family: my mother Nana Farika, wife Marie, children Kamilah and Gabrielle, brothers Marcus and Gize, sister Sahai, and my many relatives. ACKNOWLEDGEMENTS I would like to acknowledge the many who have helped me over the years: Professor Leslie Robinson, Professor Gerald Lalor, Professor Ronald Young, Professor Paul Reese, Dr. Daniel Coore, and many others at UWI who have supported my efforts over the years. Ramon and Karen Girvan, Lorna and Barry Green, Patricia Gooden-Wisdom, Trevor and Maxine Matheson, Dr. Joyce Reeves, Philippa Rhodes, all of whom helped me over the years, and many, many others. Dr. John Stasko, with whom I started this research, and my advisor, Dr. Eileen Kraemer, who went beyond the call of duty, and the members of my committee, Dr. Robert Branch, Dr. Elizabeth Davis, and Dr. Maria Hybinette. vi TABLE OF CONTENTS Page CHAPTER 1 INTRODUCTION....................................................................................................... 1 1.0 Introduction and Motivation............................................................................ 1 1.1 Algorithm Animation Studies ......................................................................... 2 1.2 Complexity of Authoring ................................................................................ 3 1.3 Our Analysis of AA Problems......................................................................... 4 1.4 HCI Design and Learning Context.................................................................. 5 1.5 Perceptual Design............................................................................................ 5 1.6 Goals and Framework of Dissertation Research ............................................. 6 1.7 Instructor Study ............................................................................................... 8 1.8 SKA................................................................................................................. 9 1.9 Perceptual Studies ......................................................................................... 10 1.10 Contributions................................................................................................. 12 1.11 Structure of Dissertation................................................................................ 13 2 ANALYZING ALGORITHM ANIMATIONS ........................................................ 15 2.0 Introduction ................................................................................................... 15 vii 2.1 Educational Technology Processes ............................................................... 15 2.2 Algorithm and Data Structure Representation .............................................. 16 2.3 Algorithm Animation Concepts .................................................................... 23 2.4 Algorithm Animation Theory........................................................................ 24 2.5 Algorithm Animation Practice ...................................................................... 27 2.6 Conclusion and Future Work ........................................................................ 32 3 THE HISTORICAL DEVELOPMENT OF ALGORITHM ANIMATION............. 33 3.0 Introduction ................................................................................................... 33 3.1 Customized Specification.............................................................................. 35 3.2 Event Annotation........................................................................................... 39 3.3 Declarative Specification .............................................................................. 47 3.4 Programming by demonstration (PBD)......................................................... 49 3.5 Automatic Visualization................................................................................ 54 3.6 Scripting ........................................................................................................ 56 3.7 Summary and Conclusion ............................................................................. 60 4 A NATURALISTIC OBSERVATIONAL STUDY OF INSTRUCTORS............... 64 4.0 Introduction and Motivation.......................................................................... 64 4.1 Related Work................................................................................................. 65 4.2 Overview and Objectives .............................................................................. 66 4.3 Study Design ................................................................................................. 67 4.4 Results ........................................................................................................... 68 4.5 Activity Analysis and Artifact Use ............................................................... 68 viii 4.6 Data Analysis ................................................................................................ 71 4.7 Data Structure Diagram Use and Tracing ..................................................... 75 4.8 Instructor Style .............................................................................................. 77 4.9 Requirements Derived from Task Analysis .................................................. 78 4.10 Conclusion..................................................................................................... 81 5 SKA: THE SUPPORT KIT FOR ANIMATION...................................................... 83 5.0 Motivation ..................................................................................................... 83 5.1 Requirements Derived from User Study and Task Analysis......................... 84 5.2 Design Approach........................................................................................... 86 5.3 Design Overview........................................................................................... 88 5.4 Usage Scenarios ............................................................................................ 91 5.5 Authoring an Animation................................................................................ 98 5.6 SKA Object Scripting.................................................................................. 100 5.7 SKA Architecture........................................................................................ 101 5.8 Visual Data Structure Development............................................................ 103 5.9 Conclusion and Future Directions............................................................... 104 6 INVESTIGATING THE ROLE OF PERCEPTION IN ALGORITHM ANIMATION 107 6.0 Introduction and Motivation.......................................................................