Interaction is increasingly a public affair, taking place in our theatres, galleries, museums, exhibitions and on the city streets. This raises a new design challenge for HCI – how should spectators experience a performer’s interaction with a computer? We classify public interfaces (including examples from art, performance and exhibition design) according to the extent to which a performer’s manipulations of an interface and their resulting effects are hidden, partially revealed, fully revealed or even amplified for spectators. Our taxonomy uncovers four broad design strategies: ‘secretive, ’ where manipulations and effects are largely hidden; ‘expressive, ’ where they tend to be revealed enabling the spectator to fully appreciate the performer’s interaction; ‘magical, ’ where effects are revealed but the manipulations that caused them are hidden; and finally ‘suspenseful, ’ where manipulations are apparent but effects are only revealed as the spectator takes their turn. ACM Classification

We present a study of people’s use of positional information as part of a collaborative location-based game. The game exploits self-reported positioning in which mobile players manually reveal their positions to remote players by manipulating electronic maps. Analysis of players ’ movements, position reports and communications, drawing on video data, system logs and player feedback, highlights some of the ways in which humans generate, communicate and interpret position reports. It appears that remote participants are largely untroubled by the relatively high positional error associated with self reports. Our analysis suggests that this may because mobile players declare themselves to be in plausible locations such as at common landmarks, ahead of themselves on their current trajectory (stating their intent) or behind themselves (confirming previously visited locations). These observations raise new requirements for the future development of automated positioning systems and also suggest that selfreported positioning may be a useful fallback when automated systems are unavailable or too unreliable.

Building on Buxton’s foreground/background model, we discuss the importance of explicitly considering both foreground interaction and background interaction, as well as transitions between foreground and background, in the design and implementation of sensing techniques for sensor-enhanced mobile devices. Our view is that the foreground concerns deliberate user activity where the user is attending to the device, while the background is the realm of inattention or split attention, using naturally occurring user activity as an input that allows the device to infer or anticipate user needs. The five questions for sensing systems of Bellotti et al. [2002] proposed as a framework for this special issue, primarily address the foreground, but neglect critical issues with background sensing. To support our perspective, we discuss a variety of foreground and background sensing techniques that we have implemented for sensor-enhanced mobile devices, such as powering on the device when the user picks it up, sensing when the user is holding the device to his ear, automatically switching between portrait and landscape display orientations depending on how the user is holding the device, and scrolling the display using tilt. We also contribute system architecture issues, such as using the foreground/background model to handle cross-talk between multiple sensor-based interaction techniques, and theoretical perspectives, such as a classification of recognition

Movements of interfaces can be analysed in terms of whether they are sensible, sensable and desirable. Sensible movements are those that users naturally perform; sensable are those that can be measured by a computer; and desirable movements are those that are required by a given application. We show how a systematic comparison of sensible, sensable and desirable movements, especially with regard to how they do not precisely overlap, can reveal potential problems with an interface and also inspire new features. We describe how this approach has been applied to the design of three interfaces: the Augurscope II, a mobile augmented reality interface for outdoors; the Drift Table, an item of furniture that uses load sensing to control the display of aerial photographs; and pointing flashlights at walls and posters in order to play sounds.

Eye-tracking systems hold some of the greatest potential among AUIs. Here, two systems that focus on eye gazing demonstrate how this simple form of visual attention can perform a level of common interactive tasks.

this paper, we describe an architecture that supports the building of context-aware services that assume context is ambiguous and allows for mediation of ambiguity by mobile users in aware environments. We discuss design guidelines that arise from supporting mediation over space and time, issues not present in the graphical user interface domain, where mediation has typically been used in the past. We illustrate the use of our architecture and the design guidelines and evaluate it through three example context-aware services, a word predictor system, an In/Out Board, and a reminder tool

Sensors are becoming increasingly important in interaction design. Authoring a sensor-based interaction comprises three steps: choosing and connecting the appropriate hardware, creating application logic, and specifying the relationship between sensor values and application logic. Recent research has successfully addressed the first two issues. However, linking sensor input data to application logic remains an exercise in patience and trial-and-error testing for most designers. This paper introduces techniques for authoring sensor-based interactions by demonstration. A combination of direct manipulation and pattern recognition techniques enables designers to control how demonstrated examples are generalized to interaction rules. This approach emphasizes design exploration by enabling very rapid iterative demonstrate-edit-review cycles. This paper describes the manifestation of these techniques in a design tool, Exemplar, and presents evaluations through a first-use lab study and a theoretical analysis using the Cognitive

An important challenge in designing ubiquitous computing experiences is negotiating transitions between explicit and implicit interaction, such as how and when to provide users with notifications. While the paradigm of implicit interaction has important benefits, it is also susceptible to difficulties with hidden modes, unexpected action, and misunderstood intent. To address these issues, this work presents a framework for implicit interaction and applies it to the design of an interactive whiteboard application called Range. Range is a public interactive whiteboard designed to support co-located, ad-hoc meetings. It employs proximity sensing capability to proactively transition between display and authoring modes, to clear space for writing, and to cluster ink strokes. We show how the implicit interaction techniques of user reflection (how systems indicate to users what they perceive or infer), system demonstration (how systems indicate what they are doing), and override (how users can interrupt or stop a proactive system action) can prevent, mitigate, and correct errors in the whiteboard’s proactive behaviors. These techniques can be generalized to improve the designs of a wide array of ubiquitous computing experiences.

In mobile devices, such as mobile phones and PDAs, an integrated camera can be used to interact with the device in new ways. In this paper we introduce the term mixed interaction space and argue that the possibility of using mixed interaction spaces is what distinguishes camerabased interaction from other types of sensor-based interaction on mobile devices. We present our implemented applications, and related work that use mixed interaction spaces. Based on this we address how mixed interaction spaces can have different identities, be mapped to applications, and how it can be visualized. Author Keywords Input and interaction technologies, augmented reality, tangible UI, interaction design. ACM Classification Keywords H5.2. User Interfaces (Interaction styles, Haptic I/O, GUI)

Seeking to be sensitive to users, smart home researchers have focused on the concept of control. They attempt to allow users to gain control over their lives by framing the problem as one of end-user programming. But families are not users as we typically conceive them, and a large body of ethnographic research shows how their activities and routines do not map well to programming tasks. End-user programming ultimately provides control of de-vices. But families want more control of their lives. In this paper, we explore this disconnect. Using grounded contextual fieldwork with dual-income families, we describe the control that families want, and suggest seven design principles that will help end-user programming systems deliver that control.