Reflection testing

In thriller films, the audience often see the character looking at themselves in a mirror or when they enter a room, you can see them in the background due to the mirror. This is usually the protagonist that you see but can occasionally be the antagonist particularly in thrillers. These are used to build tension for the audience. Reflection filming can be difficult as it as to be guaranteed that you get to see the character and make the point of why are using that shot without the camera and/or tripod being in the view.