1 thumb, 4 buttons, 20 words per minute: design and evaluation of H4-writer

We present what we believe is the most efficient and quickest four-key text entry method available. H4-Writer uses Huffman coding to assign minimized key sequences to letters, with full access to error correction, punctuation, digits, modes, etc. The key sequences are learned quickly, and support eyes-free entry. With KSPC = 2.321, the effort to enter text is comparable to multitap on a mobile phone keypad; yet multitap requires nine keys. In a longitudinal study with six participants, an average text entry speed of 20.4 wpm was observed in the 10th session. Error rates were under 1%. To improve external validity, an extended session was included that required input of punctuation and other symbols. Entry speed dropped only by about 3 wpm, suggesting participants quickly leveraged their acquired skill with H4-Writer to access advanced features.

[1]  Ken Perlin,et al.  Quikwriting: continuous stylus-based text entry , 1998, UIST '98.

[2]  I. Scott MacKenzie.  Mobile text entry using three keys , 2002, NordiCHI '02.

[3]  Kumiko Tanaka-Ishii,et al.  Entering Text with a Four-Button Device , 2002, COLING.

[4]  Brad A. Myers,et al.  EdgeWrite: a stylus-based text entry method designed for high accuracy and stability of motion , 2003, UIST '03.

[5]  I. Scott MacKenzie,et al.  Text entry using soft keyboards , 1999, Behav. Inf. Technol..

[6]  David A. Huffman,et al.  A method for the construction of minimum-redundancy codes , 1952, Proceedings of the IRE.

[7]  Marco Porta,et al.  Eye-S: a full-screen input modality for pure eye-based communication , 2008, ETRA.

[8]  I. Scott MacKenzie,et al.  KSPC (Keystrokes per Character) as a Characteristic of Text Entry Techniques , 2002, Mobile HCI.

[9]  I. Scott MacKenzie,et al.  Text Entry for Mobile Computing: Models and Methods,Theory and Practice , 2002, Hum. Comput. Interact..

[10]  Hokyoung Ryu,et al.  LetterEase: Improving text entry on a handheld device via letter reassignment , 2005, OZCHI.

[11]  Jun Gong,et al.  Alphabetically constrained keypad designs for text entry on mobile devices , 2005, CHI.

[12]  Jan Krüger,et al.  A reduced QWERTY keyboard for mobile text entry , 2004, CHI EA '04.

[13]  I. Scott MacKenzie,et al.  Input-based Language Modelling in the Design of High Performance Text Input Techniques , 2003, Graphics Interface.

[14]  I. Scott MacKenzie,et al.  Predicting text entry speed on mobile phones , 2000, CHI.

[15]  Kumiko Tanaka-Ishii,et al.  Text Entry Systems: Mobility, Accessibility, Universality , 2007 .

[16]  Roope Raisamo,et al.  Device independent text input: a rationale and an example , 2000, AVI '00.

[17]  Andriy Pavlovych,et al.  Less-Tap: A Fast and Easy-to-learn Text Input Technique for Phones , 2003, Graphics Interface.

[18]  Karin Harbusch,et al.  Towards an adaptive communication aid with text input from ambiguous keyboards , 2003 .

[19]  Geehyuk Lee,et al.  Qwerty-like 3x4 keypad layouts for mobile phone , 2005, CHI Extended Abstracts.

[20]  Brad A. Myers,et al.  Trackball text entry for people with motor impairments , 2006, CHI.

[21]  Brad A. Myers,et al.  Few-key text entry revisited: mnemonic gestures on four keys , 2006, CHI.

[22]  Mark D. Dunlop.  Watch-Top Text-Entry: Can Phone-Style Predictive Text-Entry Work with Only 5 Buttons? , 2004, Mobile HCI.

[23]  I. Scott MacKenzie,et al.  Phrase sets for evaluating text entry techniques , 2003, CHI Extended Abstracts.

[24]  Rainer Nordmann,et al.  Alternative text entry using different input methods , 2006, Assets '06.

[25]  I. Scott MacKenzie,et al.  The Immediate Usability of Graffiti , 1997, Graphics Interface.