All of these effects capitalize on our familiarity with depth's effect on shading. By shading actual objects in a way that we associate with depth, people can trick our minds into imagining space where there is not, producing some desired outcome.

Maybe my favorite example of this, and a good transition into mass media, is the short-lived game show Exit on Syfy. It used practical special effects to make safe environments seem deadly, to give the participants the illusion that there were real stakes to them winning or losing. In the challenge pictured below, they used lighting effects to make the pit seem bottomless. I couldn't find a more overhead picture, but in the show you can't see any part of the bottom. They are given a toilet plunger and a ledge to stand on as the floor pulls away, and every second they don't answer a question, their ledge retracts further into the wall. Very gripping.

While the contestants know there's no danger in this event, they still often scream and hold on to their ledge for dear life, because the darkness below seems to indicate an endless drop.