In order to observe the Ternus illusion/effect, observers view an apparent motion display known as a Ternus display. The Ternus display features a series of frames that are separated by what is known as a blank interstimulus interval (ISI). A standard Ternus display consists of three frames, sequentially presented to the observer. As can be seen in Figure 3, Frame 1 consists of three equally spread out discs that are laid out in a horizontal fashion. Frame 2 is the blank ISI which separates Frame 1 and 3 for a variable duration. Frame 3, is simply the reverse of Frame 1 with the discs on the right hand side instead. This means that the disc on the outside of Frame 1 will now appear to be in the location that the centre disc was originally in as part of Frame 1.