Excluding half audience 95%? Still may miss a lot Can't accommodate everyone Designers are not representative of the user population for whom they are designing Don't expect users to think or act like you People vary In both physical attributes and mental/cognitive attributes Number of things to control has increased dramatically Displays are more virtual/artificial Marketplace pressure Adding operations cheaper (computers)Adding controls expensive (real estate, cost) Errors are becoming Increasingly serious Design The light bulb goes on Agenda Review Design challenges Idea generation Design principles System-centered Design Focus is on the technology What can be built easily using the available tools on this particular platform? What is interesting to me, as the developer, to build? User-centered Design Design Is based on user's Abilities Needs Context Mantra: Know the user! Design Process (1) How do we come up with new (good) designs for interactive systems? Briefly revisitNorman...

Good Design Invites person to use it properly Visual affordable The perceived and actual fundamental properties of an object that help convey how it should be used (D. Norman) Guidelines for Design 1 . Provide a good conceptual model User has mental model of how things work Build design that allows user to predict effects of actions 2. Make things visible Visible performances, mappings, constraints Remind person of what can be done and how to do it Design Process (2) Why is design so difficult? Why is Design Difficult? 1. Increasing complexity/pressureNumber of things to control has risen dramatically Display is increasingly symbolic/artificial Feedback is more complex and subtle Errors are increasingly serious/costly Why Difficult? 2.

Marketplace pressures Time is money Adding functionality (complexity) is now easy and cheap Adding controls/feedback is expensive Design usually requires several iterations before success 3. People often consider cost and appearance over human factors design Style over substance 4. Creativity is challenging Can't Just make a copy Want creativity, but want pragmatism Idea CreationHow do we create and develop new interface ideas and designs? Ideas come from Imagination Analogy Observation of current practice Observation of current systems Borrow from other fields Animation Theatre Information displays Architecture Interface Metaphors Metaphor - Application of name or descriptive term to another object which is not literally applicable Use: Natural transfer - apply existing knowledge to new, abstract tasks Problem: May introduce incorrect mental model Metaphor Creation (1) Prepare What functions are needed What are users' problems?Metaphor Creation (2) Generate Use metaphor that matches users' conceptual tasks Given choice, choose metaphor closest to way system really works Ensure emotional tone is appropriate to users Metaphor Creation (3) Evaluate Evolve Idea Creation Methods 1 . Consider new use for object 2. Adapt object to be like something else 3.

Modify object for a new purpose 4. Magnify - add to object 5. Minimize - subtract from object 6. Substitute something similar 7. Rearrange aspects of object 8.

Change the point of view 9. Combine data into an ensemble Design Guidelines/PrinciplesGeneral guidelines (advice) to help create more usable systems Can be subtle, even contradictory Design Principles 1. Use simple and natural dialog in user's language Match user's task in a natural way Avoid Jargon, techno-speak Present exactly info that user needs 2. Strive for consistency Sequences, actions, commands, layout, terminology Makes more predictable 3. Provide informative feedback Continuously inform user about what is occurring Most important on frequent, substantive actions How to deal with delays? 4.

Minimize user's memory load Recognition is better than recallDescribe required input format, include example and default Use small # of generally applicable commands 5. Permit easy reversal of actions Undo! Reduces anxiety, encourages experimentation 6. Provide clearly marked exits Don't want the user to feel trapped Examples Cancel button on dialogs Interrupt/resume on lengthy operations (models) Quit - can exit anytime Reset/defaults - restore on a property sheet.