ICS 463, Intro to Human Computer Interaction Design: 4. Structured Design Dan Suthers This material will be covered primarily by working out examples in class rather than via these notes.

Levels of design (from CLG) Conceptual –Task: what does the user want to do? –Semantic: what objects, actions and methods are needed? Physical –Syntactic (Representational): what should the information displays be like? –Interaction (Operational): what I/O sequences take place?

Levels of design compared Conceptual –Task (dataflow diagrams) –Semantic (ER diagrams) Physical –Syntactic (Representational) –Interaction (Operational) Role Model Task Model Content Model (contexts, navigation) Implementation Model

Eurochange Example Validate, check request, deliver Reconstruct the dataflow diagrams How would this look in essential use case notation? Compare advantages. Entity relationship Task allocation Terminal design: too much of a jump? Since we missed last week, should we just look at your work?

Task Allocation Considerations Who performs each process and how –Information need to make a decision, and learning required –Cognitive load to decide –Available physical design options –Simplicity of task-action mapping –Handling errors –User changes mind

Physical Design Considerations Design user action/system response and representational aspects –do essential use cases belong here? Choice of –interaction style –input devices –interrupt mechanisms Attend to –Making system state visible, or observable –Consistency

Examples Put off until next week … Usage-centered example: TeleGuida Physical Consistency: Belvedere Hotmail