this paper we will argue that task knowledge structures are functionally equivalent to the knowledge structures that people possess and use when performing a task. We then go on to describe a method for identifying, analysing and modelling task knowledge structures (TKS). The contents of these TKS models can be usefully applied to the generation of design solutions. A method for applying these models to design is described. In describing TKS models and their application to design we will use examples taken from real tasks that have been analysed and real designs that have been proposed. However, because these examples are taken from complex domains we have selected them so that they will exemplify our approach rather than as complete models of the tasks within the domains

INTRODUCTION User-Centered Design (UCD) has yielded many forms of design practices in which various characteristics of the context of use are considered. Among these, task analysis is widely recognized as one fundamental way not only to ensure some user-centered design (Hackos & Redish, 1998) but to improve the understanding of how a user may interact with a user interface to accomplish a given interactive task. A task model is often defined as a description of an interactive task to be performed by the user of an application through the application's user interface. Individual elements in a task model represent specific actions that the user may undertake. Information on subtask ordering as well as conditions on task execution is also included in the model. 135 LE071-06 LE071-Diaper & Stanton LE071-Diaper-v2.cls July 30, 2003 11:20 Char Count= 0 136 LIMBOURG AND VANDERDONCKT Task analysis methods have been introduced from disciplines with different backgrounds, different concerns,

Recent work in the field of model-based user interface design offers techniques for creating and exploring user interface designs at a higher level of abstraction than is possible using traditional user interface toolkits and interface builders. The user interface designer develops a model of the proposed interactive system and expresses the model using a high-level notation; an executable prototype is then generated automatically from the model. One subclass of the model-based approaches may be characterised as task-based user interface design techniques. These techniques offer methods for creating design solutions based on information concerning the users' tasks: they provide a systematic approach that extends user interface design beyond "hacking". This technical report contains the notes for a tutorial on task-based user interface design which was originally presented at the British HCI'94 conference. The tutorial reviews the field of model-based interface design and assesses the a...

To my family For their patience, support and encouragement ACKNOWLEDGEMENTS I am grateful and indebted to the patience and guidance of Dr. Amy Pritchett, the chair of my dissertation committee, as well as the support and cooperation of all of the members of my committee: Dr. William Rouse, Dr. Julie Jacko, Dr. Ute Fischer, and Dr. Brani Vidakovic. I would like to thank Tim Roberts and Carey Odem and their entire staff at Road Ready in Duluth Georgia. Their expert knowledge of the vehicle-driving domain, the unlimited use of their fixed base automobile simulator, and their complete support afforded me resources that I did not believe were possible. Furthermore, The command and staff of the U.S. Army Aeromedical Research Laboratory, in Ft. Rucker, Alabama, specifically Mr. Arthur Estrada, provided me with the guidance, equipment, and personnel that enabled me to complete my second experiment in the NUH-60 full motion helicopter simulator located there. Other than support in logistics and academics I would like to thank my wife, JoAnna, son, Joshua, and daughter, Alana, for their patience, understanding, and encouragement for the last few years. They helped me keep focus on the importance of family throughout this process; without them in my life this work would be meaningless. Above all I want to acknowledge God’s hand in my life and the continued prayers that I have received from family, friends and members of Heritage and Acworth United Methodist Church. iv

INTRODUCTION The analysis of tasks is a fundamental and important process in many areas of applied behavioural science. Task analysis offers methods for exploring relationships between the properties of systems and user performance. Traditionally (eg. see Miller, 1962), the analyst takes descriptions of the cues that should be perceived and the actions that should be performed, and maps these onto behavioural units; but working with computers presents novel problems. It is the user's conceptual skills, not the perceptual motor skills of a previous generation of technology, that must now be automated. Successful task execution now depends critically on the user's knowledge of the system, its properties, capabilities, and requirements. Units of behaviour can no longer usefully be viewed in isolation. We shall review recent progress towards incorporating knowledge requirements into task analysis, comparing eleven forms of task analysis. All have been developed with the aim of describing k

and Social Sciences.