Design Principle

The importance of visibility of our two very different examples voice mail system to the presence and number of waiting messages invisible, and made to answer these two machines highly visible. More obvious features, the more likely users will be able to know how to do the next step. In contrast, when functions are "out of sight," which makes them more difficult to find and know how to use. Norman described the control a car to emphasize this point. For the control of the operation is clearly different visible (for example, indicators, lights, horn, hazard warning lights), to what can be done. Between the control relationship has been positioned In the car and they do makes it easy for drivers to find a suitable control or the task at hand.
The concept of visibility related to feedback. This is best illustrated by what daily life would be like without it metaphor. Imagine playing a guitar with a knife sliced bread, or use a pen to write the action, did not produce any effect if a few seconds. There will be an unbearable delay before the music making, bread is cut off, or words appear on paper, makes it almost impossible to continue under a puppet theater, saw, or stroke.
Feedback is sent back on what action has been completed, the information has been achieved, so that the person to continue its activities. Various types of audio feedback is interaction design, tactile, language, vision, and the combination. Determine which combination of different types of activities and interactivities appropriate center. The correct use of feedback can also provide user interaction necessary attention.
This refers to the mapping between the control and influence them in relationship to the world. Almost all of the cultural needs of a certain mapping between the control and whether the effect is a flashlight, automobile, power plant, or cockpit-like. Between the control and influence a good example of the mapping is up and down arrows used to...