Usability Principles

Interactive systems include anything that people perform some actions on: from doors which we open and close; to Web sites which we visit, browse, and search; to Google Glass (when it is someday a product you can buy and use yourself).

Your "reading" today is a playlist of videos on YouTube.

1. Don Norman explains that objects have affordances: Actions that the object lets you perform. Affordances can be easily perceived or they can be less apparent.

2. Don Norman demonstrates an object with poor affordances.

3. Don Norman explains conceptual models. A conceptual model is a mental representation of how an interactive system works.

4. Don Norman gives an example of an inappropriate conceptual model.

5. Don Norman explains the action cycle. Actions involve seven discrete steps: Forming goals, translating goals to tasks, sequencing tasks, executing tasks, perceiving the world, interpreting the world, and evaluating whether your goal has been achieved. Interactive systems need to support all seven stages of the action cycle.

6. Don Norman demonstrates learnability. Well-designed things aren't necessarily obvious, but they should be easy to learn.

7. David Lazarus explains Jakob Nielson's famous ten heuristics for user interface design, giving an example of each. (Zen Haiku also gives examples of the heuristics applied to life.)

8. A mini-quiz: What's wrong with the user interface depicted in this video? (I recommend watching this one twice.)