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

Topics covered


  1. 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.
  2. Chapter 9: Designing for Pleasure. In The Inmates are Running the Asylum. Cooper, A. (1999) Sams (Macmillan).
In-class activities

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.

Additional readings
  1. Task-Centered User Interface Design:  A Practical Introduction. Lewis, C. and Rieman, J. (1993). Available as Shareware. These chapters are especially relevant:
  2. Usability Inspection Methods, J. Nielsen and R. Mack (eds) (1994), Wiley and Sons.
  3. The Inmates are Running the Asylum.  Cooper, A. (1999) Sams (Macmillan).
  4. Contextual Design: Defining Customer-Centered Systems. H. Beyer and K Holtzblatt, Morgan Kaufmann Publishers
  5. 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. Morgan-Kaufmann.
  6. 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.

Last updated Summer 2004