Any action of the user should lead to an immediate reaction of the system (ideally after no more than 0.1 seconds)

Examples:

• Menu entries, object icons, etc. should become highlighted when being touched by the cursor.
• Selected items in menus should be marked.
• Path selection in navigation hierarchy should be visualized.
                                          
• Errors in user input should be reported immediately.
• System should inform the user about the status with status indicators, e.g.
• clock with rotating hands
• description of what is going on , and
• even better progress indicators (e.g., bar that progressivly indicates task completion).
  

• Feedback can be visual, auditory and tactile.
  (users should be able to turn off auditory output)

• System reactions should always have about the same latency.