A user interface display system can include at least one user responsive element. The user responsive element can include an optical mechanism. A pulsed light source can produce a light beam. Apparatus are provided for causing the light beam to repeatedly scan across the activity field. A controller can be arranged to repeatedly turn the light source on at one or more predetermined scan positions to illuminate the user responsive element. The controller can also be programed to act upon a signal regarding the status of the element. A photo detector can send the signal to the controller. The optical mechanism acts upon the light beam differently based upon the status of the user responsive element.