1. Be Consistent - represent similar concepts in similar ways
2. Provide Feedback - let the user know if they succeeded or failed in an action
3. Minimize Error Possibilities - don't even offer options that won't work
4. Provide Error Recovery - provide a clear path back from disasters
5. Accomodate Multiple Skill Levels - protect beginners; enable experts
6. Minimize Memorization - display the options and their implications

- Computer software
- Household and kitchen appliances
- Automobiles
- Architecture and Public Spaces (highways, sidewalks, parks...)

Find one GOOD and one BAD example of each of the above user interface principles in your domain. You may not be able to find all of them, but give it a good shot!

Affordance Theory

According to the psychologist James Gibson, an affordance is an activity that is made possible by some property of an object. A chair affords sitting, by being of the right shape and size and being in places where one needs to sit.

Affordances may be based on sensory (unlearned sensory experience), perceptual(learned categorizations of sensory experience) or cognitive(thought-based) processes.

The classic example of affordances involves doors and their handles. Consider the ways in which one can get into a car. You want to somehow grab the door and pull it open; most handles naturally afford this action by being so shaped that the only natural way to operate them is to pull outward.

Query 17.2:Now consider the problem of getting OUT of a car. How many ways can you list? Why do interior car door handles not have a symmetrical affordance property with exterior ones? Describe good and bad solutions to this problem.

Generalize to doors on public buildings.

Query 17.3. Explore affordances in your group's category (architecture, etc.). Try to find at least three examples of affordances and classify them concerning sensory, perceptual or cognitive attributes.