There are three models:
- Design Model, The conceptualization the designer had.
- User Model, What the user develops to explain the operations of the system.
- System Image, The physical appearance.
The aim is to align the user model and the design model. A user’s model is formed via the system model and preconceived ideas about how the system should function so it is important that the system image convey a clear picture of the design model and that the design model is simple to conceptualize.
Making things simple to Conceptualize
- Simplify the structure of the task, minimize the amount of planning or problem solving required.
- Make things visible,:
- Allow people to know what is possible.
- Allow people to understand what the effect of an action will be.
- Get the mappings right, so that users can determine:
- between intention and possible action.
- action and their effect on the system.
- actual state and perceived by sight state.
- Exploit the power of constraints.
- Make the user feel like there is only one thing to do.
- Plan for error
- When all else fails standardize, it is only useful if everybody knows it and adheres to it.
- Form the goal ( I need more light to read ).
- Form the intention ( Open the blinds or turn on the light ).
- Specify the actions needed to achieve the intention ( Plan if needed ).
- Execute the actions.
- Perceive the state of the world.
- Interpret the state of the world.
- Evaluate the outcome.
- Understand the problem
- Create a plan of action
- Execute the plan
- Evaluate the outcome
- For this to be useful it is kind of important that you have a good understanding of what is simple in regard to human cognition.