1. Apparatus for presenting images to an observer comprising a controllable light delivery medium having a display region, and an automatic controller configured to control the light delivery medium in such a way as to enable the observer to perceive a first image only when the observer's eye is in one motion state and a second image only when the observer's eye is not in the one motion state, without relying on any change in the operation of the controller or the medium as the basis for enabling the perception of the first and second images.