Design lies between the modeling and evaluation needed to determine the needs of an interface and whether the interface meets those needs. It lies conceptually above the interface software and technology. Design is where you choose the kinds of interface software and technologies that are needed for users and shape it in the way that is coherent, consistent, and aesthetically pleasing.
We distinguish between two kinds of HCI knowledge with respect to HCI: Design process and design product. Design process is how you go about arriving at an interface design. Design product is about the elements in that interface design, such as metaphor, optional support for novices, direct manipulation vs. text commands, and so on.
Design process focuses on how one comes to make design decisions. A couple of the most common processes are Ethnographic and Scandinavian. Both are about coming to really understand how the users work. Ethnographic is about involving the designer in the community to understand it. Scandinavian is about involving the actual users in the design process. Students should know about these processes and how they are actually used. Just using a good design process doesn't guarantee a good design, of course -- and some very fine designs didn't use either of these processes! A good design process keeps in mind the challenges of designing for users' constraints. The papers by Markus, Suchman, and Nardi, in particular, highlight some of the general issues of design process. The books by Beyer and Holtzblatt and by Nielsen point out whole processes for designing HCI. You'll note a good bit of redundancy between this list and those in the Modeling and Evaluation section. That's on purpose. It's not clear where the line is between understanding the user in order to model her and understanding the user in order to design something for her.
- Markus, M.L. & Keil, M. (1994) If we build it, they will come: Designing information systems people want to use. Sloan Management Review P. 11-25.
- Hughes, Sommerville,Bentley & Randall. (1993) Designing with ethnography: Making work visible. Interacting with computers. Vol 5:2. Pp. 239-253.
- Suchman, L. (1995) Making work visible. Communications of the ACM. 38:9. Pp. 56-64.
- Nardi, B. (1996) Activity theory and HCI & Studying Context. In Bonnie Nardi (Ed). Context and Consciousness: Activity theory and human computer interaction. Cambridge: MIT press.
- Kyng. M. "Scandinavian design: Users in product development", In the Proceedings of CHI'94, April 1994, pp. 3-9.
- Beyer, H & Holtzblatt, K. (1998) Contextual design: Defining customer-centered systems. San Francisco: Morgan Kaufmann.
- Nielsen, Jakob. (1994.) Usability Engineering. San Francisco: Morgan Kaufmann.
Design product is about what you actually put into the interface. The issues here have two levels:
- How you make the gross-level choices that you make. There is clearly an interaction between the interface and the task analyses that one does during modelling, e.g., direct manipulation or command-line?
- How you make the fine-grained choices that you make. Do you use a "desktop metaphor"? If not, what kinds of metaphors do you use?
Students are expected to be able to discuss issues of design with respect to the modeling process. Students should be able to talk about the kinds of tradeoffs that one might make in an interface design and why.
One of the best papers on the topic is the Gentner and Nielsen piece "The Anti-Mac Interface" (citation below). The authors describe the Mac interface in terms of the design decisions made, and then point out that completely reversing each of these design decisions also defines a reasonable and coherent interface but for a different set of users and tasks.
A classic book on the topic is Designing Interaction edited by John Carroll (1991, Cambridge University Press). The chapters on "Cognitive Artifacts" by Don Norman, "The Task-Artifact Cycle" by Caroll, Kellogg, and Rosson, "Interface Problems and Interface Resources" by Stephen Payne are particularly good for highlighting design issues at the level we're describing here.
Other relevant recommendations:
- Hutchins, E. L., Hollan, J. D., Norman, D. A., "Direct Manipulation Interfaces", in User Centered System Design: New Perspectives on Human-Computer Interaction, Donald A. Norman and Stephen W. Draper (eds), Lawrence Erlbaum Associates, Hillsdale, NJ, 1986, pp. 87-124.
- Gentner, D. and J. Nielsen (1996). "The Anti-Mac Interface." Communications of the ACM 38(8): 70-82.
- Carroll, J. M., Mack, R. L., & Kellogg, W. A. Interface metaphors and user interface design. In M. Helander (Eds.), Handbook of Human-Computer Interaction. Amsterdam; New York: Elsevier Science Publishers B.V., 1988, pp. 67-85.
- Gould, J.D & Lewis, C.H. "Designing for Usability: Key Principles, and What Designers Think." Communications of the ACM, 28(3), 1985, pp. 300-311.