Direct manipulation

The gulf of execution - the gulf of evaluation.
Know what to do and evaluate what happened after the action.

The making of gulfs. How easily can someone:

Determine the function of the device?
Tell what actions are possible?
Determine mapping from intention to physical movement?
Perform the action?
Tell what state the system is in? / if its in desired state?
Determine mapping from system state to interpretation


To reduce the gulfs, provide...
Visibility (perceived accordance or signifies)
Feedback
Consistency (also known as standards)
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 should not happen randomly