Design of Everyday Things: User Centered Design

Design should enable the user to figure out what to do and to figure out what is happening by:

• Making it easy to determine what actions are possible by using constraints
• Making the conceptual model, alternative actions, and results visible
• Making it easy to evaluate the state of the system
• Following natural mappings

Additionally, the principles of design are:

1. Use knowledge in the world and in the head
1. Knowledge in the world is useful if it is natural and easily available
2. Knowledge in the head is more efficient and therefore, design should not impede experienced users
2. Simplify
1. Minimize the amount of planning needed to complete a task
2. Understand the limits of human memory
3. Use technology to enhance visibility
4. Provide mental aids
3. Make things visible
1. The user should know what is possible and how to carry an action out
2. Actions should match intentions
3. System states should be readily apparent
4. Use good mappings
1. Relationships between intentions, actions, effects, and states should be intuitive and natural
2. Take human factors into account
5. Exploit constraints
1. Use real and imagined limitations to guide users actions
6. Design for error
1. Understand that error is inevitable
2. Make actions reversible and irreversible actions difficult to initiate
7. When all else fails, standardize
1. When good mappings aren’t possible, use standardized mappings
2. Users are trained to recognize standards
3. Standardizations are an extension of cultural constraints

Principles and practices of good design can be manipulated to make tasks that should be difficult, difficult. Guns should not be readily accessible, some doors shouldn’t be opened, etc.