Directness
Definition:
Directness is the feeling that manipulation on a representation are having
an immediate consequence on the underlying object. The underlying
object can be either a real object, a text file, or an imaginary object
such as an F-16 in an air-combat simulation. Directness is generally
associated with the concept of direct manipulation. In direct manipulation
the action being performed on the representation should be a tight match
to the operation performed on the object. In an F-16 simulator the
horizon pitches and yaws in response to a flight controller joystick.
The behavior of the horizon on screen is the same behavior one would expect
if one were actually performing the actions on the flight controller of
a real F-16. The user can begin to lose track of the metaphor and
begun to feel immersion the interface.
The tighter the fit between the input representation in the model and
real system, and the tighter the fit between the output representation
in the model and real system, the more direct the system will feel, and
the more immersed the user can become.