Robert B. Johnston

The field of ubiquitous computing was inspired by Mark Weiser's vision of computing artifacts that disappear. "They weave themselves into the fabric of everyday life until they are indistinguishable from it." Although Weiser cautioned that achieving the vision of ubiquitous computing would require a new way of thinking about computers, that takes into account the natural human environment, to date no one has articulated this new way of thinking. Here, we address this gap, making the argument that ubiquitous computing artifacts need to be physically and cognitively available. We show what this means in practice, translating our conceptual findings into principles for design. Examples and a specific application scenario show how ubiquitous computing that depends on these principles is both physically and cognitively available, seamlessly supporting living. The term 'ubiquitous computing' has been used broadly to include pervasive or context-aware computing, anytime-anywhere computing (access to the same information everywhere) and even mobile computing. Work on this 'ubiquitous computing' has been largely application driven, reporting on technical developments and new applications for RF(Radio Frequency) ID technologies, smart phones, active sensors, and wearable computing. The risk is that in focusing on the technical capabilities, the end result is a host of advanced applications that bear little resemblance to Weiser's original vision. This is a classic case of not seeing the forest for the trees. In this article, we want to take a walk in the forest, that is, to suggest a new way of thinking about how computing artifacts can assist us in living. In doing this, we draw on German philosopher Martin Heidegger's analysis of the need for equipment to be 'available.' While several influential studies in human-computer interaction (HCI) have also drawn on Heidegger and the concept of availability, these studies have focused on physical availability. While going some way to identifying and addressing the problems that Weiser identified with traditional computing, they have not gone far enough. Delving deeper into Heidegger's analysis, we can explain why artifacts designed using the traditional model of computing tend to get in the way of what we want to do. This leads us to refine the concept of physical availability and identify the need for computing artifacts to also be cognitively available. We will first draw on Heidegger to explain why it is that computing artifacts designed according to the traditional model are often a hindrance rather than a help. The traditional conception of how we use computing is based on a particular understanding of human action, which we have referred to elsewhere as the deliberative theory of action. According to this deliberative theory of action, humans reflect on the world before acting. Traditionally computing artifacts are designed to assist us through providing a representation of the world which we can reflect on before action. In other words, the traditional computing artifact requires us to move away from acting in the world to 'use' the computer. In the case of the desktop computer, there is an obvious physical move away from acting in the world to 'using' the computer. Mobile technology can bring the computer to the person in the form of laptops, handhelds and so on. However, as Figure 1 illustrates, mobility, in and of itself, does nothing to remove the dichotomy between reflecting on the world and acting in the world. We consider that Heidegger's account of how we act in the world is a truer account of everyday activity than the deliberative theory of action implicit in Figure 1. According to Heidegger's situated theory of action, we are already thrown into the world, continually responding to the situations we encounter. This means that in everyday activity we