Years ago, media guru Tony Schwartz posed a simple but interesting question. “When a horse walks across the TV screen in ‘Bonanza,’” he asked, “is it acting?”

Unlike humans (and cats), a horse doesn’t know the camera is rolling. A horse doesn’t have to pretend that it’s not aware of being filmed, but an actor does. And that is the greatest hurdle screen actors have to jump — acting as if they don’t know there’s a giant camera 2 feet away.

They also have to act as if they don’t know there are 40 people milling around behind the camera — grips, gaffers, boom operators, lead men, buyers, makeup artists, script supervisors, producers, sound engineers, set dressers, doubles, stuntmen, costume designers, camera operators, the production designer, the director of photography, the director and other actors.

In fact, all these crew members are acting, too. They are acting as if they are not in a silly business. The actors’ words come out in an eerie, unnatural silence. There is no music or ambient noise — all that will be added later. On the set, it all seems so fake, so phony. It is the very opposite of reality. Reality is noisy and uncontrolled. Filming is anything but. It is often tedious and boring.