T-Labs Series in Telecommunication Services Series editors Sebastian Möller, Berlin, Germany Axel Küpper, Berlin, Germany Alexander Raake, Berlin, Germany
More information about this series at http://www.springer.com/series/10013
Tilo Westermann User Acceptance of Mobile Notifications 123
Tilo Westermann Quality & Usability Lab Telekom Innovation Laboratories Institute of Software Engineering and Theoretical Computer Science, Berlin Institute of Technology Berlin Germany ISSN 2192-2810 ISSN 2192-2829 (electronic) T-Labs Series in Telecommunication Services ISBN 978-981-10-3850-1 ISBN 978-981-10-3851-8 (ebook) DOI 10.1007/978-981-10-3851-8 Library of Congress Control Number: 2017930420 Springer Nature Singapore Pte Ltd. 2017 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Printed on acid-free paper This Springer imprint is published by Springer Nature The registered company is Springer Nature Singapore Pte Ltd. The registered company address is: 152 Beach Road, #22-06/08 Gateway East, Singapore 189721, Singapore
The smartphone revolution is under-hyped, more people have access to phones than access to running water. We ve never had anything like this before since the beginning of the planet. Marc Lowell Andreessen, founder of Netscape
Acknowledgements On completion of my dissertation I would like to sincerely thank all those who supported me in realizing and finishing my work. Over the past years, I have been fortunate to work together with great colleagues, of whom some turned into good friends, who made the time at the Quality and Usability Lab of TU Berlin an outstanding experience. Foremost, I would like to express my special appreciation and thanks to my principal supervisor Prof. Dr.-Ing. Sebastian Möller, you have been a tremendous mentor for me. Thank you for your continuous support over the course of the years! This thesis would not have been possible without you. I would also like to thank my committee members, Prof. Dr. Georg Essl and Prof. Dr. Thorsten Staake. I highly appreciate your agreement to and commitment on co-examining my thesis. A significant part of this work resulted from the close cooperation with Dr.-Ing. Ina Wechsung, who has always been a great and discerning colleague. Thank you for introducing me to the world of statistical analysis and not getting tired of questions. I will always cherish the memories shared with my colleagues Florian Hinterleitner, Justus Beyer, Benjamin Bähr, Prof. Dr.-Ing. Jens Ahrens, Dr. Benjamin Weiss, and Stefan Hillmann. From foosball to kitesurfing, these memories will surely remain. Thank you also to Irene Hube-Achter, Yasmin Hillebrenner, and Tobias Hirsch for the organizational support. You are doing a great job! Many thanks to all the students, whom I had the pleasure to supervise for their own theses and who worked with me as student assistants. Of course, not only people closely related to my work supported me in realizing this thesis. Dr.-Ing. Aubrey Schmidt, who initially established the contact to Prof. Dr.-Ing. Sebastian Möller, which eventually led to my Diploma thesis at the Quality and Usability Lab, has been a constant source of inspiration. Thank you for proofreading this thesis and providing valuable feedback. Also thanks to Joshua Marr and Christoph Szeppek, who voluntarily read parts of this work. vii
viii Acknowledgements Finally, nothing would have been possible without my family. I am infinitely grateful for your support over the years. And Daniela, thank you for giving me so much support and understanding.
Contents Part I Introduction and Motivation 1 Introduction... 3 1.1 Challenges and Motivation... 5 1.2 Research Questions... 5 1.3 Thesis Outline... 6 Part II Background 2 Background and Related Work... 9 2.1 Mobile Human-Computer Interaction... 9 2.1.1 Limitation of Attention... 9 2.1.2 Information Processing... 10 2.2 Technical Background... 12 2.2.1 Permission Models on Smartphones: Accessing Protected Resources... 13 2.2.2 Mechanisms for Notifications on Smartphones... 14 2.3 Research Methodology... 17 2.3.1 Leveraging Mobile Application Stores... 18 2.3.2 Methodically Related Studies... 21 2.3.3 Methodically Related Frameworks... 23 2.3.4 Ethics... 24 2.4 Related Work... 26 2.4.1 General Usage of Mobile Phones and Smartphones... 26 2.4.2 Warnings and Permission Requests... 29 2.4.3 Adaptation of Settings on Smartphones... 32 2.4.4 Notifications and Interruptions... 33 2.5 Summary... 38 ix
x Contents Part III Technical Framework 3 Framework and Testbed for Tracing Mobile Application Usage... 43 3.1 Introduction... 43 3.2 Prerequisites... 44 3.3 Mobile Applications: Native, Web, and Hybrid Solutions... 45 3.3.1 Native Applications... 45 3.3.2 Mobile Web Applications... 45 3.3.3 Hybrid Applications... 46 3.3.4 Design Decision: Constraints and Requirements... 46 3.4 Conceptual Framework... 46 3.4.1 Tracing Mobile Application Usage... 47 3.4.2 Gathering User Feedback... 50 3.4.3 Recording Interaction with Notifications on a System-Wide Level... 52 3.4.4 Summary... 53 3.5 Domain-Specific Mobile Applications... 54 3.5.1 Sense4En... 54 3.5.2 QUe... 56 3.5.3 Klügste Nacht... 58 3.6 Summary... 59 Part IV Studies 4 Global Analysis of User Behavior in the Field... 63 4.1 Introduction... 63 4.2 Methodology... 63 4.2.1 Participants... 63 4.2.2 Procedure... 64 4.3 General Application Usage... 67 4.4 Notification Handling... 69 4.4.1 Factors Influencing Seen Time... 70 4.4.2 Factors Influencing Notification Handling... 72 4.4.3 The Role of Notification Presentation... 73 4.4.4 Annoying Notifications & Stress... 73 4.4.5 The Influence of Notifications on Application Usage... 76 4.5 Discussion... 77 4.6 Conclusion... 78 5 Permission Requests and Notification Settings... 81 5.1 Introduction... 81 5.2 Study B: Notification Settings Across Categories... 82 5.2.1 Introduction... 82 5.2.2 Methodology... 82
Contents xi 5.2.3 Results... 86 5.2.4 Discussion... 88 5.2.5 Limitations... 88 5.3 Design Concept for Permission Requests... 89 5.4 Study C: Permission Request Characteristics... 91 5.4.1 Introduction... 91 5.4.2 Methodology... 91 5.4.3 Results... 93 5.4.4 Discussion... 95 5.5 Study D: Trust and Privacy... 96 5.5.1 Introduction... 96 5.5.2 Methodology... 97 5.5.3 Results... 98 5.5.4 Discussion... 100 5.6 Conclusion... 102 6 Receptivity to Notifications... 103 6.1 Introduction... 103 6.2 Study E: Modality, Actionability, and Perceived Importance... 104 6.2.1 Introduction... 104 6.2.2 Methodology... 104 6.2.3 Results... 106 6.2.4 Discussion... 108 6.3 Study F: Content and Frequency... 109 6.3.1 Introduction... 109 6.3.2 Pre-study... 109 6.3.3 Field Study... 112 6.3.4 Discussion... 114 6.4 Study G: Context Factor Time... 115 6.4.1 Introduction... 115 6.4.2 Methodology... 115 6.4.3 Results... 117 6.4.4 Discussion... 119 6.5 Conclusion... 120 Part V Conclusion 7 General Conclusions... 125 7.1 Summary... 125 7.2 Conclusion... 126 7.3 Limitations... 129
xii Contents 7.4 Future Work... 130 7.4.1 From Short-Term to Long-Term Studies... 130 7.4.2 From Smartphone to Other Smart Devices... 130 7.4.3 From Tool to Assistant... 130 7.4.4 From System-Initiated to User-Initiated... 131 Appendix A: Technostress Questionnaire... 133 Bibliography... 135
Acronyms App Application ANOVA Analysis of variance API Application programming interface APNs Apple Push Notification service C-HIP Communication human information processing CRM Customer relationship management CPU Central processing unit ESM Experience sampling method EULA End-user license agreement GCM Google Cloud Messaging ICT Information and communication technology IM Instant messaging JSON JavaScript Object Notation HCI Human computer interaction HTML HyperText Markup Language HTML5 Hypertext markup language (Version 5) HTTP Hypertext Transfer Protocol LED Light-emitting diode mhci mobile Human-Computer Interaction MTurk Amazon Mechanical Turk OS Operating system PC Personal computer PDA Personal digital assistant SAM Self-Assessment Manikin SMS Short message service TLS Transport Layer Security ubicomp Ubiquitous computing UI user interface UML Unified Modeling Language URL Uniform Resource Locator xiii
xiv Acronyms UTC UX WLAN Coordinated Universal Time User experience Wireless local area network
Abstract Smartphones have become an indispensable part of everyday life. Due to technological achievements and a growing number of applications available, the smartphone increasingly becomes a multi-purpose tool. It does not only affect digital media consumption, but also daily behaviors from the physical world that migrate to digital platforms. In order not to get lost in the shuffle, applications are competing for users attention. Notifications are a core feature of many applications, proactively pushing new content to users. In contrast to the traditional pull approach of requesting information, push technology transfers the initiative from the user to the system. The number of applications utilizing this channel to increase user engagement is growing, potentially causing information overload. The issues that may arise with notifications, e. g., the interruption of a user s task, have been recognized in the research community, and strategies for limiting disruption have been proposed, e. g., deferring notifications to opportune moments for interruption. However, it might not be preferable to defer all notifications, as some may require immediate attention, e. g., a message from one's partner telling that one needs to pick up the children from kindergarten. A great number of the proposed strategies include services that handle notifications on the user s behalf. This dissertation takes an alternative approach, starting with an understanding of user s acceptance of mobile notifications in order to provide tools supporting users in managing these. It extends previous research by investigating factors influencing users perception of notifications and proposing tools addressing shortcomings of current systems. A technical framework and testbed is designed and implemented as an approach for evaluating the usage of mobile applications and notifications. Based on this framework, a series of studies investigating factors influencing users perception of mobile notifications is presented. According to the studies, notifications on smartphones may raise awareness, but were also identified as a contributor to creating stress. If users are given the choice of opting in to receiving notifications, as for example on Apple s ios platform, managing expectations by providing explanations of the nature of notifications seems to be a promising step towards xv
xvi Abstract informed decisions. In addition, providing readily available settings for notifications was found to be valued by users. Still, notifications are not perceived equally; particularly those that are related to people are perceived as least annoying. Results further suggest that the situated interplay of contextual and user factors eventually determines users perception. Finally, a set of design guidelines for the usage of mobile notifications is derived that may be employed to support users in handling notifications on smartphones.