PaperPhone: Understanding the Use of Bend Gestures in Mobile Devices with Flexible Electronic Paper Displays Byron Lahey 1,2 , Audrey Girouard 1 , Winslow Burleson 2 and Roel Vertegaal 1 1 Human Media Lab School of Computing, Queen’s University Kingston, Ontario, K7L 3N6 Canada 2 Motivational Environments Research Group Arizona State University Tempe, Arizona, AZ 85281, USA {lahey,audrey,roel}@cs.queensu.ca, winslow.burleson@asu.edu ABSTRACT Flexible displays potentially allow for interaction styles that resemble those used in paper documents. Bending the dis- play, e.g., to page forward, shows particular promise as an interaction technique. In this paper, we present an evalua- tion of the effectiveness of various bend gestures in execut- ing a set of tasks with a flexible display. We discuss a study in which users designed bend gestures for common compu- ting actions deployed on a smartphone-inspired flexible E Ink prototype called PaperPhone. We collected a total of 87 bend gesture pairs from ten participants and their appropri- ateness over twenty actions in five applications. We identi- fied six most frequently used bend gesture pairs out of 24 unique pairs. Results show users preferred bend gestures and bend gesture pairs that were conceptually simpler, e.g., along one axis, and less physically demanding. There was a strong agreement among participants to use the same three pairs in applications: (1) side of display, up/down (2) top corner, up/down (3) bottom corner, up/down. For actions with a strong directional cue, we found strong consensus on the polarity of the bend gestures (e.g., navigating left is performed with an upwards bend gesture, navigating right, downwards). This implies that bend gestures that take di- rectional cues into account are likely more natural to users. Author Keywords Flexible Displays, E Ink, Bend Gestures, Organic User In- terfaces ACM Classification Keywords H.5.2. Information interfaces and presentation: User Inter- faces – Interaction styles, evaluation/methodology, user- centered design. INTRODUCTION While research in the domain of flexible display interfaces has been ongoing for the better part a decade, there is, to our knowledge, little to no user interface research where actual flexible displays were deployed. Most of the display technologies used in prior studies were either based on sim- ulations using projection on paper [10], rigid LCD displays on a flexible substrate [20] or paper mockups [13]. These methods of simulating real flexible displays potentially in- troduce biases for the evaluation of interactions. By using real flexible displays and integrated bend sensing we achieve interactions that align with the performance charac- teristics of devices that could be commercially available in the immediate future. While there may be suggestions that bending of a flexible display can be as effective and effi- cient an input technique as button controls in rigid displays for tasks like paging, the case for the use of flexible over rigid screens is not necessarily based on the superior effi- ciency of interactions. Indeed, much work is required for flexible touch screens to become as effective as rigid ones. However, while rigid screens may continue to have the edge in terms of interaction efficiency for some time, we believe there are sufficient practical and interactional rea- sons for flexible displays to achieve mass adoption. The likely reason for adoption of flexible displays is that they may closely approximate the look and feel of paper docu- Figure 1. The PaperPhone prototype with flexible E Ink dis- play features bend gesture input recognition. Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. CHI 2011, May 7–12, 2011, Vancouver, BC, Canada. Copyright 2011 ACM 978-1-4503-0267-8/11/05...$5.00.