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Helsinki University of Technology Publications in Telecommunications Software and Multimedia Teknillisen korkeakoulun tietoliikenneohjelmistojen ja multimedian julkaisuja Espoo 2004 TML-A8 Evolution and Usability of Mobile Phone Interaction Styles Harri Kiljander Helsinki University of Technology Publications in Telecommunications Software and Multimedia Teknillisen korkeakoulun tietoliikenneohjelmistojen ja multimedian julkaisuja Espoo 2004 TML-A8 Evolution and Usability of Mobile Phone Interaction Styles Harri Kiljander Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Computer Science and Engineering for public examination and debate in Auditorium T2 at Helsinki University of Technology (Espoo, Finland) on the 3rd of December, 2004, at 12 o'clock noon. Helsinki University of Technology Department of Computer Science and Engineering Telecommunications Software and Multimedia Laboratory Teknillinen korkeakoulu Tietotekniikan osasto Tietoliikenneohjelmistojen ja multimedian laboratorio Distribution: Helsinki University of Technology Telecommunications Software and Multimedia Laboratory P.O.Box 5400 FIN-02015 HUT Tel. +358-9-451 2870 Fax. +358-9-451 5014 © 2004 Harri Kiljander ISBN 951-22-7319-5 ISSN 1456-7911 Otamedia Oy Espoo 2004 Abstract Author Harri Kiljander Title Evolution and Usability of Mobile Phone Interaction Styles Over one billion people own or use cellular mobile telephones. Therefore, industry practitioners are faced with a question: how big steps can they take when designing the user interfaces for their new products, or how closely should they stick with the already existing user interface conventions that may already be familiar to the consumers. The objective of this research work is to create and communicate new knowledge for design and usability practitioners about how to design and evolve interaction style conventions in mainstream, voice-centric mobile telephones. In the context of this study, interaction style denotes the framework consisting of the physical interaction objects, the abstract interaction elements, and the associated behavior or interaction conventions that are applied throughout the core functionality of the mobile phone, but excludes the stylistic appearance elements of the user interface. The main research problem — how do mobile phone interaction style changes affect the initial usability of a mobile phone for users with earlier experience with mobile phones — is approached via several methods. A literature study compares the interaction styles applied in mainstream computing domains against the aspects relevant in the mobile phones domain. A heuristic analysis of contemporary mobile phones is used to formulate an understanding of the available interaction styles and analyze whether there is convergence towards specific types of interaction styles in the industry. An empirical usability testing experiment with 38 test users is conducted with a novel mobile phone interaction style to investigate differences between users who are already familiar with different mobile phone interaction styles. The study reveals that interaction styles applied in contemporary mobile telephones are designed around menu navigation, and they implement the three primary operations — Select, Back and Menu access — with dedicated hardkeys, context-sensitive softkeys, or using special control devices like joysticks or jog dials. The control keys in the contemporary interaction styles are converging around various two- and three-softkey conventions. The aspects related to indirect manipulation and small displays pose specific usability and UI design challenges on mobile phone user interfaces. The study shows that the mobile handset manufacturers are applying their usually proprietary interaction styles in a rather consistent manner in their products, with the notable exception of mobile Internet browsers that often break the underlying interaction style consistency. Based on the results from the empirical usability testing, we claim that despite differences between interaction styles in contemporary mobile phones, users do not face significant difficulties when transferring to a novel mobile phone model. UDC 621.396.93:004.5:65.015.11 Keywords Mobile telephone, user interface, interaction style, interface style, usability testing, initial use, learnability 1 2 “Today, switching from one phone to another, or from one carrier to another, requires learning new menus and screen designs. The differences -- maddening as they are -- rarely add any value to the user experience.” — BusinessWeek, 21-Nov-2002 "Dad. What do I press? There is no red key." — Kristian Kiljander, 5 years 3 4 Preface The research work reported in this thesis has been conducted in the cellular mobile telephones research and development environment at Nokia. This is not a traditional academic research setting but instead a more business-driven, product creation project environment. Likewise, the spirit and approach in this study is applied research. During 1995 – 1997 I was conducting mobile phone usability research work, and participated in several user interface concept creation projects at Nokia Research Center. In 1998 – 1999 I was working as a usability engineer in communicator and mobile phone product development at Nokia Mobile Phones. In 1998 I was also nominated to the Nokia-internal doctoral development program, which gave a concrete boost to this thesis work. In 1999 – 2000 my team’s responsibilities included the creation of the mobile phone user interface strategy and roadmap of the company. During 2001 – 2002 I was heading another team in the user interface software development organization; now involved with the user interface design management and usability activities for Nokia’s high-volume mobile handsets. From 2003 I have been working on the holistic management of Nokia’s mobile terminal user interfaces and UI policies. These different viewpoints to cellular mobile telephones usability research, user interface design and development, and strategic decision-making gradually have made me realize that there is a need for a more thorough and solid understanding of the application of the various user interface elements the industry is commonly applying in mobile telephones. The importance of ease-of-use as a product attribute is generally acknowledged, user-friendliness is a buzzword frequently used by top executives, and user-centered design methods are commonplace in the product creation process. However, I believe there are still gaps in our understanding of how we should evolve the products’ user interfaces when a growing number of users already have experience in using a mobile phone. Similarly, there are signs and attempts of user interface convergence in the industry, and we should better understand what to converge and how to harmonize. I believe this thesis will increase and deepen the level of knowledge in these issues. Tapiola, 31st October 2004 Harri Kiljander [email protected] 5 6 Acknowledgements Carrying out a doctoral thesis project outside an academic research environment has not been a very straightforward task, and definitely has not happened without the support of a large number of people. My warmest thanks go to Professor Tapio “Tassu” Takala as the supervisor of this work for the guidance, tutoring, and inspiration throughout my doctoral studies. It’s been rewarding and fun to be a student of him since my first computer graphics course back in 1989. I would like to express my gratitude to Professors Timo Jokela from University of Oulu and Turkka Keinonen from University of Art and Design Helsinki as the external pre-examiners of this thesis work for their profound and elaborate contribution to improve the research methodology and the quality of the dissertation manuscript. Very special thanks are addressed to John Rieman, PhD. It’s a privilege to know and work with true professionals; his mentoring and support has been instrumental throughout the dissertation project and especially when setting up the empirical usability testing experiment and carrying out the statistical analysis of the test results. I would like to thank Ms. Aino Ahtinen, Ms. Tuula Varis, and Mr. Matti Helenius for conducting the empirical usability testing and test results analysis, and Ms. Dana McKay for her contribution in the heuristic mobile phone UI analysis. I am also grateful to Professor Kaisa Väänänen-Vainio- Mattila, Dr. Timo Kaltio, Dr. Pekka Ketola, and Mr. Topi Koskinen for their valuable contribution to improve the dissertation manuscript. I would also like to thank Mr. Erik Anderson, Mr. Christian Lindholm, and Mr. Harri Wikberg — the creative minds behind many of Nokia’s highly successful mobile user interfaces — for shaping or challenging my thinking of mobile device user interface design and evolution. My special thanks go to Dr. Yrjö Neuvo, for the initial inspiration and boost I received during the Leading Science course in 1998, and to my brother-in-law Mr. Jorma Korpijärvi, who has been keeping the summer house project alive while I have been occupied with the dissertation. I was also supported financially by the Nokia Foundation. This grant, together with a sabbatical period generously arranged by my former superior, Mr. Craig Livingstone, made it possible for me to focus full-time on the dissertation project during the summer of 2002. I would also like to thank Ms. Titti Kallio and her usability team at TeliaSonera, Mr. Bruno von Niman from vonniman