In this paper, we question the assumption that seamless integration of computer system components is necessarily a design requirement for wearable computing and for ubiquitous computing. We explore Mark Weiser's notions of seamlessness and 'seamfulness', and use them in discussing the design and use of wearable and ubicomp systems. The physical nature of the systems we design reveals itself in, for example, uncertainty in sensing, limited coverage of communications infrastructure, and the transformations needed to share data between heterogeneous tools and media. When such seams show through, as they inevitably do, users perceive and appropriate them for their own uses. However, we suggest that new opportunities for system design arise if we take fuller account of this process. We offer examples of seams and some suggestions for seamful design, drawing from the Equator interdisciplinary research collaboration's work on ubiquitous computing and mixed reality systems. More particularly, we focus on our work in Equator's City project, on a system that lets a visitor using a PDA in a museum exhibition or cultural institution co-visit with people using virtual reality and web versions of the same institution. Our work is strongly influenced by the vision of ubiquitous computing presented by Mark Weiser (1). One of the broader design goals of ubicomp is invisibility: A good tool is an invisible tool. By invisible, I mean that the tool does not intrude on your consciousness; you focus on the task, not the tool. In other words, one no longer needs to attend to the tool when using it. Ubiquity involves multiple, heterogeneous devices providing highly dispersed input, output and computational capabilities. These parts collectively form a tool for interaction that is "literally visible, effectively invisible" because their design, along with one's experience and understanding of them, lets one focus on interaction through the whole instead of on the parts-just as a carpenter does carpentry without a constant and conscious focus on his hammer. However, it appears that this notion of invisibility has been translated into requirements for seamless integration of computer system components, as well as the interactions supported by those components. Seamlessness is an attractive prospect, extending the ideas of metaphoric direct manipulation to make our interactions with computers more literal, reducing the distractions that such interactions currently introduce. However, Weiser describes seamlessness as a misleading or misguided concept. In his invited talks at UIST94 (2) and USENIX95 (3), he suggests that making things seamless amounts to making everything the same, and he advocates seamful systems (with "beautiful seams") as a goal. Paraphrasing Weiser's talk slides only slightly, and retaining his emphasis: making everything the same is easy; letting everything be itself, with other things, is hard. To Weiser, making every place the same meant mobile and distributed technology offering access to information in ways that do not take account of the particular character of the place one is in. Similarly, making every tool the same meant reducing components, tools and systems to their 'lowest common denominator'. Around Xerox PARC, Weiser complained that 'seamless design' meant sacrificing the richness of each tool in order to obtain bland compatibility, for example when one tool is chosen as primary and the others are reduced and simplified so that they conform to it (personal communication). Seamfully integrated tools would maintain the unique characteristics of each tool, through transformations that retained their individual characteristics. Interaction would be seamless even though the features of each tool were apparent. Part of ubicomp was seamful design, where integration may be hard but the quality of interaction is improved by letting each tool 'be itself'. Weiser suggests to us that "the unit of design should be social people, in their environment, plus your device". A device that senses, models and lets the user take advantage of the context of 'other things', such as nearby people and the non-digital objects in their environment, is of course well-established within the ubicomp community. We suggest, however, that letting a ubicomp system be itself means accepting all its physical and computational characteristics-that may either be weaknesses or strengths. A user's activity is influenced by what they perceive and understand of sensors, transducers and other I/O devices, and the system's internal models and infrastructure. For example, mobile phone signal strength is a physical property of the system infrastructure that is sensed and made apparent to phone users in everyday use through the phone's interface, and also through whether they can hear people clearly, make a call, get an Internet connection, and so on. Experience of signal strength offers a credible excuse for not returning a call, or for ending a call early-sometimes even when the signal is strong. Users usually do not want or need
In other words, a seamful design framework is centered around the idea of deliberately revealing seams to users and taking advantage of features usually considered as negative or problematic REF ].
M.: Seamful design: Showing the seams in wearable computing
In: Proceedings of IEE Eurowearable 2003
Engineering