Design Principles: 1. Direct manipulation.
- Our first lesson is that in both transit and in cookware, simply asking people what they want can often miss important opportunities.
- The second is that you can find these problems and opportunities — like poor ergonomics — by going out into the field and discovering what people actually do.
- And, third, you can get extra power out of this observation by bringing prototypes along with you.
- Fourth, the world is full of people tinkering in their garage, and everyone wins when the stars align to bring those things into the world.
With measuring cups, like user interfaces, you can think of there as being two steps: The first is having some action.
And the second is evaluating the outcome.
At each of these steps, you, as a designer, has an opportunity for success or for failure.
In our first step, what you have to cross is the gulf of execution: How does the user know what to do?
And the gulf that you have to help the user cross is the gulf of evaluation: How does the user know what happened?
As a designer, here are six powerful questions that you can ask to ascertain what challenges may arise:
- Determine the function of the device?
- Tell what actions are possible?
- Determine mapping from intention to physical movement?
4. Perform the action?
5. Tell what state the system is in? / If its in desired state
6. Determine mapping from system state to interpretation
To reduce the gulfs, provide…
- Visibility (percieved affordances or signifiers)
- Non-destructive operations (hence the importance of undo)
- Discoverability: All operations can be discovered by systematic exploration of menus
- Reliability. Operations should work. Period. And events shouldn’t happen randomly.