Notes on the Design of Everyday Things
Principles of design for understandibility and usability
- Provide a good conceptual model
- Make things visible
- The Principle of Mapping
- The Principle of Feedback
The three requirements for a system to be explorable:
- In each state of the system, the user must readily see and be able to do the allowable actions.
- The results of the action must be both visible and easy to interpret.
- Actions should be without cost
Seven principles for transforming difficult tasks into simple ones:
- Use both knowledge in the world and knowledge in the head
- Simplify the structure of tasks
- Make things visible: bridge the gulf of Execution and Evaluation.
- Get the mappings right
- Exploit the power of contraints both natural and artificial
- Design for error
- When all else fails, standardize
Re: mapping. Make sure the user can determine the relationships:
- between intentions and possible actions
- between actions and the effects on the system
- between actual system state and what is perceivable by sight, sound, or feel
- between the perceived system state and the needs, intentions, and expectations of the user
Whenever the number of functions and required operations exceeds the number of controls, the design becomes arbitrary, unnatural and complicated.
People usually blame themselves for errors
When there is a problem, people are apt to focus on it to exclusion of other factors, thus performing dangerous actions like sticking a knife in the toaster to get a stuck piece of bread.