On–The–Go Text Entry: Evaluating and Improving Mobile Text Input on Mini–Qwerty Keyboards
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ON{THE{GO TEXT ENTRY: EVALUATING AND IMPROVING MOBILE TEXT INPUT ON MINI{QWERTY KEYBOARDS A Thesis Presented to The Academic Faculty by James Clawson In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the School of Interactive Computing Georgia Institute of Technology December 2012 ON{THE{GO TEXT ENTRY: EVALUATING AND IMPROVING MOBILE TEXT INPUT ON MINI{QWERTY KEYBOARDS Approved by: Dr. Thad Starner, Adviser Dr. Scott MacKenzie School of Interactive Computing Department of Computer Science and Georgia Institute of Technology Engineering York University Dr. Gregory Abowd Dr. Jacob Wobbrock School of Interactive Computing Information School Georgia Institute of Technology University of Washington Dr. Elizabeth Mynatt Date Approved: 12 November 2012 School of Interactive Computing Georgia Institute of Technology To my fianc´ee, Dana Habeeb, without your love and support, none of this would have been possible. Thank you. iii ACKNOWLEDGEMENTS There is absolutely no way that I would be where I am in my dissertation or my research without the endless encouragement, inspiration, criticism, patience, and sup- port of my advisor, Dr. Thad Starner. We have worked together for years exploring text entry, use-in-motion, and mobile HCI challenges in general. We have successfully published a number of papers and grants together and this is a direct result of his tireless enthusiasm, his insatiable curiosity, and his ability to kindly guide a novice researcher through the process of conducting and communicating research. Thad is one of the most brilliant, selfless, and inspiring people I have encountered and it has been a true honor to work with him these past eight years. Thank you Thad for always being a patient teacher, a generous intellect, a late night writing companion, a creative story teller, and a friend. Thanks also goes to my Ph.D. Advisory Committee: Gregory Abowd, Beth My- natt, Scott MacKenzie, and Jacob Wobbrock. Gregory, thank you always for your insightful and challenging questions. Your ability to cut to the heart of the mater and find the intellectual nugget is simply amazing. I have often said that ten minutes of your time is worth an hour of anyone else's. Beth, I feel like you have always looked out for me. I have always appreciated your ability to take time out of your busy schedule and prioritize things you value even when the job demands 200% of your time. Thank you for all of your support all of these years. I look forward to joining your lab and starting the next stage of my career with you. To my local committee contingent, you three are the best that there are, I can't tell you how lucky I feel that you agreed to serve on my committee. I can never thank you enough for you inspiration and guidance. iv Scott, having the world expert on your committee can be a little intimidating for a Ph.D. student. Your enthusiasm and encouragement however won me over from the very beginning and working with you has been an amazing experience. You are a wonderful communicator and a fantastic person who I hope to be able to work with for many years to come. Finally, Jake. Jake, I asked you to be on my committee years ago because I wanted to model myself after you. Young, impetuous, diligent, and brilliant, you were able to turn an early text entry research agenda into a successful career that rose above and beyond stylus input to the point where your work impacts people from many walks of life. You have been an inspiration and a friend over the years and I'm flattered that our relationship evolved into one of peers. Thanks for your advice and help along the way and of course, thank you for your research insight. To my external committee members, my research is heavily influenced by the work you have done and I thank you for both blazing the path and providing a guiding light. To the ccg past, present, and future: I can not thank each and every one of you enough for your help, guidance, challenges, mentorship, patience and love. Kent and Nirmal, from beginning to end you two have been amazing. Thanks for being the heart of the the mobileHCI team. Kim, Helene, Val, and Tracy: the ladies of the ccg. Your crazy friendship, counseling, support, and encouragement over the years is truly appreciated. To ccg juniors like Tanya, Quigs, Daniel, Scott, and Clint; thanks for always working hard, listening well, and taking the advice of your peers with a grain of salt. You guys will do wonderful things. I look forward to seeing you grow as researchers. Lastly I would like to acknowledge the love and support I received from my family and friends. To my 401 family, thanks for everything. You're really the best extended family a guy could have. To my parents and siblings, aunts and uncles, and Grand- daddy: I know it has been a long and, at times, rocky road. Thanks for sticking with v me and for all of the love and support along the way. I really couldn't have done it without you. And finally, to Dana and Dessie: you are my life. I love you and thanks! vi TABLE OF CONTENTS DEDICATION .................................. iii ACKNOWLEDGEMENTS .......................... iv LIST OF TABLES ............................... xi LIST OF FIGURES .............................. xv SUMMARY .................................... xvii I INTRODUCTION ............................. 1 1.1 Thesis Statement . .2 1.2 Contributions . .2 1.3 Overview of the Dissertation . .2 II RELATED WORK ............................. 7 2.1 Mobile Keyboards . .7 2.2 Mini{QWERTY Keyboards . .9 2.3 Mobile Text Entry On-the-Go . 11 2.3.1 Controlled Use{In{Motion Studies . 12 2.3.2 Typing on-the-go . 14 2.4 Text Entry Evaluations . 15 2.5 Accuracy Measurements in Text Entry Studies . 16 2.6 Measuring Speed in Text Entry Studies . 20 III AN EMPIRICAL STUDY OF TYPING PERFORMANCE ON MINI{QWERTY KEYBOARDS .................... 21 3.1 Method . 21 3.1.1 Participants . 21 3.1.2 Equipment and Software . 22 3.2 Design and Procedure . 25 3.3 Results . 25 3.3.1 Survey Results . 27 vii 3.4 Discussion . 28 IV THE IMPACTS OF LIMITED VISUAL FEEDBACK ON MINI- QWERTY KEYBOARD ENABLED MOBILE TEXT ENTRY . 30 4.1 Blind Typing in Real Environments . 31 4.2 A Taxonomy for Blind Mobile Text Input . 31 4.3 Method . 35 4.3.1 Design and Procedure . 36 4.3.2 Equipment and Software . 37 4.4 Results . 37 4.5 Blind Discussion . 39 V TEXTING WHILE WALKING: AN EVALUATION OF MINI- QWERTY TEXT INPUT WHILE ON-THE-GO .......... 42 5.1 Evaluation . 45 5.1.1 Participants . 46 5.1.2 Equipment and Software . 46 5.1.3 Procedure . 47 5.1.4 Study Design . 50 5.2 Results . 52 5.2.1 Training to expertise . 53 5.2.2 Mobility Conditions . 54 5.3 Discussion . 55 VI AN ANALYSIS OF MINI{QWERTY KEYBOARD TYPING ER- RORS IN VARIOUS CONTEXTS OF USE. ............. 57 6.1 Errors in mini-QWERTY keyboard typing . 57 6.1.1 Analysis of errors from the Baseline study . 58 6.1.2 Analysis of errors from the mobile evaluation . 60 6.1.3 Mobile Errors: Sitting vs. Standing vs. Walking . 63 6.1.4 Semantic Errors . 66 6.2 Discussion . 70 viii VII AUTOMATIC WHITEOUT: LEVERAGING FEATURES OF THE USER'S INPUT TO CORRECT ERRORS IN MINI{QWERTY TYPING ................................... 72 7.1 Automatic Whiteout . 73 7.2 Experimental Data . 76 7.2.1 Sampling the Experimental Data . 77 7.2.2 Datasets: Dell complete, Dell expert, Targus complete, and blind . 81 7.2.3 Training . 82 7.3 The Evaluation of Automatic Whiteout . 82 7.3.1 Generalization Across User Expertise . 83 7.3.2 Generalization Across Keyboards . 84 7.3.3 Generalization Across Different Visibility Conditions . 85 7.3.4 Generalization Across Corpora . 86 7.3.5 Sensitivity to Timing . 89 7.4 Conclusion . 89 VIIIFATTHUMBS: A SET OF SIMPLE RULES USED TO DETECT AND CORRECT OFF-BY-ONE ERRORS ............. 92 8.1 Training on improved data . 93 8.2 New features that utilize key-up and key-down information . 94 8.3 Training new decision trees . 98 8.3.1 Sample decision tree . 100 8.4 A set of simple rules . 103 8.4.1 Detecting Roll-off Errors . 104 8.4.2 Detecting Roll-on Errors . 107 8.4.3 Detecting Equal Downtime Errors . 107 8.5 Discussion . 107 IX FATTHUMBS EVALUATION ..................... 109 9.1 Equipment and Software . 109 9.2 Participants . 110 ix 9.3 Study Design . 111 9.4 Results . 112 9.4.1 FatThumbs performance . 114 9.4.2 FatThumbs performance . 117 9.4.3 Participant reaction . 119 X DISCUSSION AND FUTURE WORK ................ 122 10.1 Summary . 122 10.2 Discussion . 127 10.2.1 Training participants to expertise . 127 10.2.2 Live Error Correction vs. Retrospective Results . 129 10.2.3 Improving FatThumbs . 129 10.2.4 Decision Trees as a Visualization Tool . 131 10.3 Future Work . 132 XI CONCLUSION ............................... 135 APPENDIX A | FEATURES ...................... 138 APPENDIX B | EXAMPLE OF A VERY SELECTIVE DECISION TREE ..................................... 144 APPENDIX C | THE DOCUMENT SHARED WITH PARTIC- IPANTS DETAILING THE PURPOSE OF THE FATTHUMBS EVALUATION ............................... 151 APPENDIX D | FULL INTERVIEW TRANSCRIPTS FROM THE FATTHUMBS EVALUATION ..................... 152 REFERENCES .................................. 176 x LIST OF TABLES 1 Summary of research questions . .4 2 Mean mini{QWERTY typing rates and standard deviations for Session 1 and Session 20. 26 3 Mean mini{QWERTY error rates and standard deviations for Session 1 and Session 20. 26 4 Mean desktop typing rates and standard deviations for before session 1 and after session 20.