How to measure usability is an important question in HCI research and user interface evaluation. We review current practice in measuring usability by categorizing and discussing usability measures from 180 studies published in core HCI journals and proceedings. The discussion distinguish several problems with the measures, including whether they actually measure usability, if they cover usability broadly, how they are reasoned about, and if they meet recommendations on how to measure usability. In many studies, the choice of and reasoning about usability measures fall short of a valid and reliable account of usability as quality-in-use of the user interface being studied. Based on the review, we discuss challenges for studies of usability and for research into how to measure usability. The challenges are to distinguish and empirically compare subjective and objective measures of usability; to focus on developing and employing measures of learning and retention; to study long-term use and usability; to extend measures of satisfaction beyond post-use questionnaires; to validate and standardize the host of subjective satisfaction questionnaires used; to study correlations between usability measures as a means for validation; and to use both micro and macro tasks and corresponding measures of usability. In conclusion, we argue that increased attention to the problems identified and challenges discussed may strengthen studies of usability and usability research.

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Current practice in measuring usability: Challenges to usability studies and research

This paper makes seven recommendations to HCI researchers wishing to construct Fitts' law models for either movement time prediction, or for the comparison of conditions in an experiment. These seven recommendations support (and in some cases supplement) the methods described in the recent ISO 9241-9 standard on the evaluation of pointing devices. In addition to improving the robustness of Fitts' law models, these recommendations (if widely employed) will improve the comparability and consistency of forthcoming publications. Arguments to support these recommendations are presented, as are concise reviews of 24 published Fitts' law models of the mouse, and 9 studies that used the new ISO standard.

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Towards a standard for pointing device evaluation, perspectives on 27 years of Fitts' law research in HCI

Finally-a thorough pedagogical survey of the multidisciplinary science of HCI.

Human-Computer Interaction spans many disciplines, from the social and behavioral sciences to information and computer technology. But of all the textbooks on HCI technology and applications, none has adequately addressed HCI's multidisciplinary foundations-until now. 

HCI Models, Theories, and Frameworks fills a huge void in the education and training of advanced HCI students. Its authors comprise a veritable house of diamonds-internationally known HCI researchers, every one of whom has successfully applied a unique scientific method to solve practical problems.

Each chapter focuses on a different scientific analysis or approach, but all in an identical format, especially designed to facilitate comparison of the various models.

HCI Models, Theories, and Frameworks answers the question raised by the other HCI textbooks: 
How can HCI theory can support practice in HCI?
* Traces HCI research from its origins
* Surveys 14 different successful research approaches in HCI
* Presents each approach in a common format to facilitate comparisons
* Web-enhanced with teaching tools at http://www.HCImodels.com

*Contributors are leading researchers in the field of Human-Comptuter Interaction 

*Fills a major gap in current literature about the rich scientific foundations of HCI 

*Provides a thorough pedogological survey of the science of HCI

Table of Contents

Acknowledgments

1. Introduction: Toward a Multidisciplinary Science of Human-Computer Interaction
by John M. Carroll, Virginia Tech 

2. Design as Applied Perception
by Colin Ware, University of New Hampshire

3. Motor Behavior Models for Human-Computer Interaction
by I. Scott MacKenzie, York University, Toronto, Canada

4. Information Processing and Skilled Behavior
by Bonnie E. John, Carnegie Mellon University

5. Notational Systems--The Cognitive Dimensions of Notations Framework by Alan Blackwell and Thomas Green, Cambridge University, Cambridge, England

6. Users' Mental Models: The Very Ideas
by Stephen J. Payne, Cardiff University, Wales

7. Exploring and Finding Information
by Peter Pirolli, Palo Alto Research Center

8. Distributed Cognition
by Mark Perry, Brunel University, London, England

9. Cognitive Work Analysis
by Penelope M. Sanderson, University of Queensland, Australia

10. Common Ground in Electronically Mediated Communication: Clark's Theory of Language Use
by Andrew Monk, University of York, England

11. Activity Theory
by Olav W. Bertelsen and Susanne Bodker, University of Aarhus, Denmark

12. Applying Social Psychological Theory to the Problems of Group Work
by Robert E. Kraut, Carnegie Mellon University

13. Studies of Work in Human-Computer Interaction
by Graham Button, Xerox Research Centre Europe, Grenoble, France

14. Upside-Down Vs and Algorithms-Computational Formalisms and Theory
by Alan Dix, Lancaster University, England

15. Design Rationale as Theory
by John M. Carroll and Mary Beth Rosson, Virginia Tech

HCI Models, Theories, and Frameworks: Toward a Multidisciplinary Science

We show how modern mobile phones (Weiser's tabs) can interact with their environment, especially large situated displays (Weiser's boards). Smart phones' emerging capabilities are fueling a rise in the use of mobile phones as input devices to such resources as situated displays, vending machines, and home appliances. Mobile phones' prevalence gives them great potential to be the default physical interface for ubiquitous computing applications. We survey interaction techniques that use mobile phones as input devices to ubiquitous computing environments. We use smart phone to describe an enhanced mobile phone. Our analysis blurs the line between smart phones and PDAs such as the Palm Pilot because the feature sets continue to converge.

The smart phone: a ubiquitous input device

The ongoing pilot clinical trial of the BrainGate neural interface system aims in part to assess the feasibility of using neural activity obtained from a small-scale, chronically implanted, intracortical microelectrode array to provide control signals for a neural prosthesis system. Critical questions include how long implanted microelectrodes will record useful neural signals, how reliably those signals can be acquired and decoded, and how effectively they can be used to control various assistive technologies such as computers and robotic assistive devices, or to enable functional electrical stimulation of paralyzed muscles. Here we examined these questions by assessing neural cursor control and BrainGate system characteristics on five consecutive days 1000 days after implant of a 4 × 4 mm array of 100 microelectrodes in the motor cortex of a human with longstanding tetraplegia subsequent to a brainstem stroke. On each of five prospectively-selected days we performed time-amplitude sorting of neuronal spiking activity, trained a population-based Kalman velocity decoding filter combined with a linear discriminant click state classifier, and then assessed closed-loop point-and-click cursor control. The participant performed both an eight-target center-out task and a random target Fitts metric task which was adapted from a human-computer interaction ISO standard used to quantify performance of computer input devices. The neural interface system was further characterized by daily measurement of electrode impedances, unit waveforms and local field potentials. Across the five days, spiking signals were obtained from 41 of 96 electrodes and were successfully decoded to provide neural cursor point-and-click control with a mean task performance of 91.3% ± 0.1% (mean ± s.d.) correct target acquisition. Results across five consecutive days demonstrate that a neural interface system based on an intracortical microelectrode array can provide repeatable, accurate point-and-click control of a computer interface to an individual with tetraplegia 1000 days after implantation of this sensor.

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Neural control of cursor trajectory and click by a human with tetraplegia 1000 days after implant of an intracortical microelectrode array

In view of the difficulties in evaluating computer pointing devices across different tasks within dynamic and complex systems, new performance measures are needed. This paper proposes seven new accuracy measures to elicit (sometimes subtle) differences among devices in precision pointing tasks. The measures are target re-entry, task axis crossing, movement direction change, orthogonal direction change, movement variability, movement error, and movement offset. Unlike movement time, error rate, and throughput, which are based on a single measurement per trial, the new measures capture aspects of movement behaviour during a trial. The theoretical basis and computational techniques for the measures are described, with examples given. An evaluation with four pointing devices was conducted to validate the measures. A causal relationship to pointing device efficiency (viz. throughput) was found, as was an ability to discriminate among devices in situations where differences did not otherwise appear. Implications for pointing device research are discussed.

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Accuracy measures for evaluating computer pointing devices

Meeting the increasing demand for desktop-like applications on mobile products requires powerful interaction techniques. One candidate is GUI-style point-and-click interaction using an integrated pointing device that supports handheld use. We tested an isometric joystick for this purpose. Two prototypes were built. They were designed for thumb operation and included a separate selection button. Twelve participants performed point-and-select tasks. We tested both one-handed and two-handed interaction, and selection using the separate selection button and the joystick's integrated press-to-select feature. A notebook configuration served as a reference. Results for the handheld conditions, both one-handed and two-handed, were just slightly off those for the notebook condition, suggesting that an isometric joystick is suitable as a pointing device for handheld terminals. Inadvertent selection while moving the pointer yielded high error rates for all conditions using press-to-select. A separate select button is therefore needed to ensure accurate selection.

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An isometric joystick as a pointing device for handheld information terminals

A terminal includes a display and a user interface. The terminal also includes means for providing the terminal display with at least one virtual display, a display portion or an object, and means for moving at least the virtual display, the display portion or the object on the display using the motion of the terminal or the motion and/or location of an object proportioned to the terminal.

Tatu Kauppinen

Papers

Accuracy measures for evaluating computer pointing devices

An isometric joystick as a pointing device for handheld information terminals

Method for controlling a terminal display and a terminal