INVESTIGATING RETROSPECTIVE INTEROPERABILITY BETWEEN THE ACCESSIBLE AND MOBILE WEBS WITH REGARD TO USER INPUT A thesis submitted to the University of Manchester for the degree of Doctor of Philosophy in the Faculty of Engineering and Physical Sciences 2011 By Tianyi Chen School of Computer Science Contents Abstract 13 Declaration 15 Copyright 16 Acknowledgements 17 1 Introduction 18 1.1 Problem Statement . 21 1.2 Research Questions . 23 1.3 Thesis Structure . 25 1.4 Publications . 27 2 Background and Related Works 31 2.1 Web Accessibility . 31 2.2 Guidelines & Best Practices . 33 2.2.1 Web Content Accessibility Guidelines . 34 2.2.2 User Agent Accessibility Guidelines & Authoring Tools Ac- cessibility Guidelines . 35 2.2.3 Mobile Web Best Practices . 37 2.3 Mobile Web . 37 2.4 Overlapping experiences between the Accessible and the Mobile Webs . 40 2.4.1 Visual Impariment . 41 2.4.2 Hearing Impairment . 42 2.4.3 Physical Impairment . 43 2.4.4 Cognitive Impairment . 44 2 2.4.5 Older Users . 44 2.5 Input Problems Affecting Disabled Desktop Users and Mobile Web Users . 46 2.5.1 Text Input . 49 2.5.2 Pointing (Target Acquisition) . 56 3 Small Device User Evaluation While Seated 63 3.1 Methodology . 66 3.1.1 Participants . 66 3.1.2 Apparatus and Venue . 66 3.1.3 Tasks . 68 3.1.4 Procedure . 70 3.2 Data Analysis . 71 3.3 Typing Task Results . 73 3.3.1 Overall Performance . 73 3.3.2 Key Ambiguity Error . 77 3.3.3 Additional Key Error . 78 3.3.4 Missing Key Error . 78 3.3.5 Bounce Error . 79 3.3.6 Transposition Error . 82 3.3.7 Long Key Press Error . 82 3.4 Pointing Task Results . 83 3.4.1 Overall Performance . 83 3.4.2 Clicking Errors . 85 3.4.3 Multi-clicking Errors . 86 3.4.4 Dragging Errors . 88 3.4.5 Comparison of Pointing Errors . 91 3.5 Discussion . 92 3.5.1 Overlaps Between Accessible and Mobile Webs . 92 3.5.2 Task Completion Time, Correction Time and Experiences 93 3.5.3 Key Ambiguity Errors . 94 3.5.4 Correlation Between Error Rates and Subjective Ratings . 95 3.5.5 Clicking Difficulties . 95 3.5.6 Multi-Clicking Difficulties . 96 3.5.7 Dragging Difficulties . 96 3.5.8 Typing Long Text on Small Devices . 96 3 3.5.9 Limitation of the study . 97 3.6 Conclusions . 97 4 Investigating Use Patterns of Small Device Users 99 4.1 Related Work . 101 4.2 Methodology . 104 4.3 Observational Study Results . 108 4.3.1 Typing While Walking . 108 4.3.2 Typing with Just One Hand . 108 4.3.3 Rapid Attention Switches . 110 4.4 Interview Results . 112 4.4.1 Using Small Devices While Walking . 112 4.4.2 Typing with Just One Hand . 112 4.4.3 Using a Physical Keypad . 112 4.4.4 More Attention Switches While Walking or Accompanied . 113 4.4.5 Using the Mobile Web . 115 4.5 Patterns of Small Device Users . 116 4.6 Protocol for Designing User Evaluation with Small Device Users . 120 4.6.1 Step-by-Step Design . 120 4.6.2 General Guidance . 122 4.7 Conclusions . 125 5 Small Device User Evaluations While Walking 127 5.1 Methodology . 128 5.1.1 Participants & Experimenters . 128 5.1.2 Tasks . 129 5.1.3 Route . 129 5.1.4 Procedure . 134 5.1.5 Apparatus . 135 5.2 Data Analysis . 138 5.3 Typing Task Results . 142 5.3.1 Subjective Ratings . 143 5.3.2 Typing Errors . 144 5.4 Pointing Task Results . 151 5.4.1 Time . 151 5.4.2 Subjective Ratings . 152 4 5.4.3 Pointing Errors . 153 5.5 Comparison with Previous Study . 158 5.5.1 Comparing Typing Error Rates . 158 5.5.2 Comparing Pointing Error Rates . 164 5.6 Confirmatory Study . 164 5.7 Conclusions . 168 6 Solution Migration 170 6.1 Proposed Migration . 171 6.1.1 Dynamic Keyboard . 171 6.1.2 TrueKeys . 172 6.1.3 Target Expansion . 172 6.1.4 Steady Clicks System . 173 6.1.5 Sticky Icons with Adaptive Gain Control . 174 6.1.6 SUPPLE & SUPPLE++ . 175 6.2 A Typing Error Correction System . 176 6.2.1 System Architecture . 177 6.2.2 Error Correction Algorithms . 177 6.3 User Evaluation . 180 6.3.1 Typing Task Results . 182 6.4 Conclusions . 185 7 Conclusions and Future Work 187 7.1 Thesis Overview . 188 7.2 Contributions of the Thesis . 189 7.2.1 Motor-Impaired Desktop Users and the Mobile Web Users Share Common Input Problems . 189 7.2.2 The Error Rates of Input Errors Increase in Magnitude as Small Device Users Become Mobile . 190 7.2.3 Existing Solution Migrated from the Motor-Impaired Desk- top User Domain Benefits the Mobile Web Users . 191 7.3 Outstanding Issues . 192 7.4 Future Work . 193 A Typing Task Instruction Form 215 B Pointing Tasks Instruction Form 216 5 C Editing Tasks Instruction Form 219 D Field Study Data Recording Form 222 E Webpages Used in the Study 224 F Demographic Form 231 G Session Record Form 234 H Technical Reports 237 6 List of Tables 2.1 Text Input Accessibility Issues and Corresponding Solutions. ∗Situationally{ Induced Impairments . 47 2.2 Pointing Related Accessibility Issues and Corresponding Solutions. ∗Situationally{Induced Impairments . 48 3.1 Typing and pointing errors that affect motor impaired desktop users 64 3.2 Subjective ratings of our participants for their previous experience of text entry and the mobile Web (1= none, 5= expert) . 67 3.3 Total keystrokes, time and correction time for the typing task (T1) and its repetition (T2) . 74 3.4 Number of typing errors in the typing task (T1) and its repetition (T2) . 76 3.5 Participants' subjective ratings on avoiding typing errors (1= very difficult, 7=very easy) . 77 3.6 Total time and correction time spent on the pointing task (P1), editing task (E) and repetition of the pointing task (P2) . 84 3.7 Participants' subjective ratings on pointing performance (1= very difficult, 7= very easy) . 85 3.8 A comparison of typing and pointing errors of mobile Web users and motor impaired desktop users Note: Even though the number of errors cannot be statistically com- pared because of the differences in both studies, They are provided here to give an idea about the errors experienced by both user groups. 93 4.1 Questions asked in the interviews . 107 4.2 Genders and age ranges of the interviewees . 112 4.3 Possible values of the mobility pattern and hand usage pattern . 117 5.1 The roles of experimenters . 128 7 5.2 Actions required for pointing tasks T1, T4 and T7 . 130 5.3 Text materials used for typing tasks T2, T5 and T8 . 130 5.4 Task conditions and corresponding sub-routes and checkpoints . 132 5.5 Typing errors identified in the sitting experiment . 140 5.6 Pointing errors identified in the sitting experiment . 140 5.7 Time spent on each task . 141 5.8 Characters entered by each participant . ..