Trajectory-based interactions, such as navigating through nested-menus, drawing curves, and moving in 3D worlds, are becoming common tasks in modern computer interfaces. Users' performances in these tasks cannot be successfully modeled with Fitts' law as it has been applied to pointing tasks. Therefore we explore the possible existence of robust regularities in trajectory-based tasks. We used "steering through tunnels" as our experimental paradigm to represent such tasks, and found that a simple "steering law" indeed exists. The paper presents the motivation, analysis, a series of four experiments, and the applications of the steering law.

Current input device taxonomies and other frameworks typically emphasize the mechanical structure of input devices. We suggest that selecting an appropriate input device for an interactive task requires looking beyond the physical structure of devices to the deeper perceptual structure of the task, the device, and the interrelationship between the perceptual structure of the task and the control properties of the device. We atllrm that perception is key to understanding performance of multidimensional input devices on multidimensional tasks. We have therefore extended the theory of processing of perceptual structure to graphical interactive tasks and to the control structure of input devices. This allows us to predict task and device combinations that lead to better performance and hypothesize that performance is improved when the perceptual structure of the task matches the control structure of the device. We conducted an experiment in which subjects performed two tasks with different perceptual structures, using two input devices with correspondingly different control structures, a three-dimensional tracker and a mouse. We analyzed both speed and accuracy, as well as the trajectories generated by subjects as they used the unconstrained three-dimensional tracker to perform each task. The results support our hypothesis and confirm the importance of matching the perceptual structure of the task and the control structure of the input device. Categories and Subject Descriptors: H.1.2 [Models and Principles]: User/Machine

This article introduces a new interaction model called Instrumental Interaction that extends and generalizes the principles of direct manipulation. It covers existing interaction styles, including traditional WIMP interfaces, as well as new interaction styles such as two-handed input and augmented reality. It defines a design space for new interaction techniques and a set of properties for comparing them. Instrumental Interaction describes graphical user interfaces in terms of domain objects and interaction instruments. Interaction between users and domain objects is mediated by interaction instruments, similar to the tools and instruments we use in the real world to interact with physical objects. The article presents the model, applies it to describe and compare a number of interaction techniques, and shows how it was used to create a new interface for searching and replacing text. Keywords Interaction model, WIMP interfaces, direct manipulation, post-WIMP interfaces, instrumental ...

Note that the text that appeared in printed journal contains very minor typographic and grammatical corrections that do not appear in this version. SpeechSkimmer:

This article proposes and tests a two-component model for describing and programming the finegrained aspects of non-WIMP interaction. The model combines a data-flow or constraint-like component for the continuous relationships with an event-based component for discrete interactions, which can enable or disable individual continuous relationships. Its key ingredients are the separation of non-WIMP interaction into two components and the framework it provides for communication between the two

Multimodal interaction enables the user to employ different modalities such as voice, gesture and typing for communicating with a computer. This paper presents an analysis of the integration of multiple communication modalities within an interactive system. To do so, a software engineering perspective is adopted. First, the notion of "multimodal system" is clarified. We aim at proving that two main features of a multimodal system are the concurrency of processing and the fusion of input/output data. On the basis of these two features, we then propose a design space and a method for classifying multimodal systems. In the last section, we present a software architecture model of multimodal systems which supports these two salient properties: concurrency of processing and data fusion. Two multimodal systems developed in our team, VoicePaint and NoteBook, are used to illustrate the discussion.

Despite intense and wide-spread research in both virtual environments (VEs) and usability, the exciting new technology of VEs has not yet been closely coupled with the important characteristic of usability -- a necessary coupling if VEs are to reach their full potential. Although numerous methods exist for usability evaluation of interactive computer applications, these methods have well-known limitations, especially for evaluating VEs. Thus, there is a great need to develop usability evaluation methods and criteria specifically for VEs. Our goal is to increase awareness of the need for usability engineering of VEs and to lay a scientific foundation for developing high-impact methods for usability engineering of VEs. The first step in our multi-year research plan has been accomplished, yielding a comprehensive multi-dimensional taxonomy of usability characteristics specifically for VEs. This taxonomy was developed by collecting and synthesizing information from literature, conferences, World Wide Web (WWW) searches, investigative research visits to top VE facilities, and interviews of VE researchers and developers. The taxonomy consists of four main areas of usability issues: Users and User Tasks in VEs, general user and task characteristics and types of tasks in VEs

The literature has long suggested that the design of computer input devices should make use of the fine, smaller muscle groups and joints in the fingers, since they are richly represented in the human motor and sensory cortex and they have higher information processing bandwidth than other body parts. This hypothesis, however, has not been conclusively verified with empirical research. The present work studied such a hypothesis in the context of designing 6 degree-of-freedom (DOF) input devices. The work attempts to address both a practical need- designing efficient 6 DOF input devices- and the theoretical issue of muscle group differences in input control. Two alternative 6 DOF input devices, one including and the other excluding the fingers from the 6 DOF manipulation, were designed and tested in a 3D object docking experiment. Users ' task completion times were significantly shorter with the device that utilised the fingers. The results of this study strongly suggest that the shape and size of future input device designs should constitute affordances that invite finger participation in input control.

This paper reviews the existing literature on input device evaluation and design in human-computer interaction (HCI) and discusses possible applications of this knowledge to the design and evaluation of new interfaces for musical expression. Spression.5; a set of musical tasks is suggested to allow the evaluation of different existing controllers.

This paper focuses on enabling interactions with large public displays using the most ubiquitous personal computing device, the mobile phone. Two new interaction techniques are introduced that use the embedded camera on mobile phones as an enabling technology. The “Point & Shoot” technique allows users to select objects using visual codes to set up an absolute coordinate system on the display surface instead of tagging individual objects on the screen. The “Sweep ” technique enables users to use the phone like an optical mouse with multiple degrees of freedom and allows interaction without having to point the camera at the display. Prototypes of these interactions have been implemented and evaluated using modern mobile phone technologies. This proof of concept provides a performance baseline and gives valuable insights to guide future research and development. These techniques are intended to inspire and enable new classes of large public display applications. Categories & Subject Descriptors: H.5.2 [Information Interfaces