Publication statistics

Pub. period:1994-1998
Pub. count:6
Number of co-authors:8


Number of publications with 3 favourite co-authors:

Ken Hinckley:6
Randy Pausch:5
Dennis Proffitt:3



Productive colleagues

Neal F. Kassell's 3 most productive colleagues in number of publications:

Ken Hinckley:54
Randy Pausch:31
Randy F. Pausch:12

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Neal F. Kassell


Publications by Neal F. Kassell (bibliography)

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Hinckley, Ken, Pausch, Randy, Proffitt, Dennis and Kassell, Neal F. (1998): Two-Handed Virtual Manipulation. In ACM Transactions on Computer-Human Interaction, 5 (3) pp. 260-302. Available online

We discuss a two-handed user interface designed to support three-dimensional neurosurgical visualization. By itself, this system is a "point design," an example of an advanced user interface technique. In this work, we argue that in order to understand why interaction techniques do or do not work, and to suggest possibilities for new techniques, it is important to move beyond point design and to introduce careful scientific measurement of human behavioral principles. In particular, we argue that the common-sense viewpoint that "two hands save time by working in parallel" may not always be an effective way to think about two-handed interface design because the hands do not necessarily work in parallel (there is a structure to two-handed manipulation) and because two hands do more than just save time over one hand (two hands provide the user with more information and can structure how the user thinks about a task). To support these claims, we present an interface design developed in collaboration with neurosurgeons which has undergone extensive informal usability testing, as well as a pair of formal experimental studies which investigate behavioral aspects of two-handed virtual object manipulation. Our hope is that this discussion will help others to apply the lessons learned in our neurosurgery application to future two-handed user interface designs.

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Hinckley, Ken, Pausch, Randy, Proffitt, Dennis, Patten, James and Kassell, Neal F. (1997): Cooperative Bimanual Action. In: Pemberton, Steven (ed.) Proceedings of the ACM CHI 97 Human Factors in Computing Systems Conference March 22-27, 1997, Atlanta, Georgia. pp. 27-34. Available online

We present an experiment on cooperative bimanual action. Right-handed subjects manipulated a pair of physical objects, a tool and a target object, so that the tool would touch a target on the object (fig. 1). For this task, there is a marked specialization of the hands. Performance is best when the left hand orients the target object and the right hand manipulates the tool, but is significantly reduced when these roles are reversed. This suggests that the right hand operates relative to the frame-of-reference of the left hand. Furthermore, when physical constraints guide the tool placement, this fundamentally changes the type of motor control required. The task is tremendously simplified for both hands, and reversing roles of the hands is no longer an important factor. Thus, specialization of the roles of the hands is significant only for skilled manipulation.

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Hinckley, Ken, Tullio, Joe, Pausch, Randy, Proffitt, Dennis and Kassell, Neal F. (1997): Usability Analysis of 3D Rotation Techniques. In: Robertson, George G. and Schmandt, Chris (eds.) Proceedings of the 10th annual ACM symposium on User interface software and technology October 14 - 17, 1997, Banff, Alberta, Canada. pp. 1-10. Available online

We report results from a formal user study of interactive 3D rotation using the mouse-driven Virtual Sphere and Arcball techniques, as well as multidimensional input techniques based on magnetic orientation sensors. Multidimensional input is often assumed to allow users to work quickly, but at the cost of precision, due to the instability of the hand moving in the open air. We show that, at least for the orientation matching task used in this experiment, users can take advantage of the integrated degrees of freedom provided by multidimensional input without necessarily sacrificing precision: using multidimensional input, users completed the experimental task up to 36% faster without any statistically detectable loss of accuracy. We also report detailed observations of common usability problems when first encountering the techniques. Our observations suggest some design issues for 3D input devices. For example, the physical form-factors of the 3D input device significantly influenced user acceptance of otherwise identical input sensors. The device should afford some tactile cues, so the user can feel its orientation without looking at it. In the absence of such cues, some test users were unsure of how to use the device.

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Goble, John C., Hinckley, Ken, Pausch, Randy F., Snell, John W. and Kassell, Neal F. (1995): Two-Handed Spatial Interface Tools for Neurosurgial Planning. In IEEE Computer, 28 (7) pp. 20-26.

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Hinckley, Ken, Pausch, Randy, Goble, John C. and Kassell, Neal F. (1994): Passive Real-World Interface Props for Neurosurgical Visualization. In: Adelson, Beth, Dumais, Susan and Olson, Judith S. (eds.) Proceedings of the ACM CHI 94 Human Factors in Computing Systems Conference April 24-28, 1994, Boston, Massachusetts. pp. 452-458. Available online

We claim that physical manipulation of familiar real-world objects in the user's real environment is an important technique for the design of three-dimensional user interfaces. These real-world passive interface props are manipulated by the user to specify spatial relationships between interface objects. By unobtrusively embedding free-space position and orientation trackers within the props, we enable the computer to passively observe a natural user dialog in the real world, rather than forcing the user to engage in a contrived dialog in the computer-generated world. We present neurosurgical planning as a driving application and demonstrate the utility of a head viewing prop, a cutting-plane selection prop, and a trajectory selection prop in this domain. Using passive props in this interface exploits the surgeon's existing skills, provides direct action-task correspondence, eliminates explicit modes for separate tools, facilitates natural two-handed interaction, and provides tactile and kinesthetic feedback for the user. Our informal evaluation sessions have shown that with a cursory introduction, neurosurgeons who have never seen the interface can understand and use it without training.

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Hinckley, Ken, Pausch, Randy, Goble, John C. and Kassell, Neal F. (1994): A Survey of Design Issues in Spatial Input. In: Szekely, Pedro (ed.) Proceedings of the 7th annual ACM symposium on User interface software and technology November 02 - 04, 1994, Marina del Rey, California, United States. pp. 213-222. Available online

We present a survey of design issues for developing effective free-space three-dimensional (3D) user interfaces. Our survey is based upon previous work in 3D interaction, our experience in developing free-space interfaces, and our informal observations of test users. We illustrate our design issues using examples drawn from instances of 3D interfaces. For example, our first issue suggests that users have difficulty understanding three-dimensional space. We offer a set of strategies which may help users to better perceive a 3D virtual environment, including the use of spatial references, relative gesture, two-handed interaction, multisensory feedback, physical constraints, and head tracking. We describe interfaces which employ these strategies. Our major contribution is the synthesis of many scattered results, observations, and examples into a common framework. This framework should serve as a guide to researchers or systems builders who may not be familiar with design issues in spatial input. Where appropriate, we also try to identify areas in free-space 3D interaction which we see as likely candidates for additional research. An extended and annotated version of the references list for this paper is available on-line through mosaic at address

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