Task-Centered System Design
Task-centered system design is a technique that
helps developers design and evaluate interfaces based on users' real-world tasks. As
part of design, it becomes a user-centered requirements analysis (with the requirements being the
tasks that need to be satisfied). As part of evaluation, the evaluator can do a
walk-through of the prototype, using the tasks to generate a step by step scenario of what
a user would have to do with the system. Each step in the walkthrough asks the questions:
is it believable that a person would do this; and does the person have the knowledge to do
it? If not, then a bug has been found.
An assignment on task-centered design
and prototyping provides students with hands-on practice in task articulation
and prototype walkthrough.
Handouts and resources
- The task-centered system design process
- Developing task examples
- Task scenarios and walkthroughs
- Case study: CheapShop
- Working through Task-Centered System Design.
Greenberg, S. (2003)
in Diaper, D. and Stanton, N. (Eds) The Handbook of Task Analysis for
Human-Computer Interaction. Lawrence Erlbaum Associates.
- This chapter provides an introduction and worked example of the
task-centered design process. It is directly based on the materials taught
in this class.
Chapter 9: Designing for Pleasure.
In The Inmates are Running the Asylum. Cooper, A. (1999) Sams
- This chapter describes goal-centered system design, a related
methodology. It discusses how one can use Personas to influence design.
To make this material come alive, the class will apply task-centered system design
to "Cheap Shop", a catalogue-based store. In this case study, the situation is that Cheap Shop's
customers now browse through paper catalogues and then place their orders by filling in a
form and giving it to the clerk. Cheap Shop is replacing the paper forms by a
computer interface. A previously created design has already been proposed (provided in the exercise mentioned above).
Several task examples were created after the fact, and these are used by the class
to evaluate this design. The class walks each user identified in
the examples through the task step
by step. Of course, the class will discover many deficiencies. Afterards, an alternative design
for Cheap Shop (detailed in the prototyping module) is developed. Reading 1
details this exercise as a case study.
- Task-Centered User Interface
Design: A Practical Introduction.
Lewis, C. and Rieman, J. (1993). Available as
Shareware. These chapters are especially relevant:
- Chapter 1: Getting
to Know Users and their Tasks
- Chapter 4:
Evaluating the Design Without Users
- Usability Inspection Methods, J. Nielsen and R. Mack (eds) (1994),
Wiley and Sons.
- Cognitive and pluralistic walkthroughs are highly related techniques
that influence the way I present this material. This book has several
chapters on these methods:
- Chapter 3: The pluralistic usability walkthrough: Coordinated
Empathies. Bias, R.G.
- Chapter 5: The cognitive walkthrough method: A practitioner's
guide. Wharton, C., Rieman, J., Lewis, C. and Polson, P.
- The Inmates are Running the Asylum. Cooper, A. (1999) Sams
- An applied and fun book appropriate to lay interface developers. Chapter
9 was mentioned above, but Chapter 11 also relates to this topic.
- Contextual Design: Defining Customer-Centered Systems. H. Beyer
and K Holtzblatt, Morgan Kaufmann Publishers
- describes a detailed methodology for articulating tasks, and is highly
recommended if you are analyzing complex situations.
- Chapter 3: Considering Work Contexts in Design. p.187-272. In
Baecker, R., Grudin, J., Buxton, W., and Greenberg, S., eds (1995).
Readings in Human Computer Interaction:
Towards the Year 2000.
Playacting and focus troupes: Theatre techniques of creating quick,
intense, immersive, and engaging focus group sessions. Sato, S. and
Salvador, T. (1999) interactions, 6(5), September/October.
- This chapter focuses on the interplay between the
design of computer systems and applications, as well as the social and
organizational settings in which they are to be used. It goes far beyond the
sometimes simplistic view of task-centered system design by considering the
entire work context: from user centered, to organization-centered, to the
sociology of work, and to workplace computerization.
- describes a
techniques for discovering uses of brand new products with no precursors.
Last updated Summer 2004