Question to all you film buffs
I've started watching my xmas present, the box set of Star Trek the Original Series. (You can all be jealous now) Last night on the episode, The Enemy Within, due to a transporter accident Cpt. Kirk is split into two people, his kind, compassionate, caring side and his aggressive evil side. When they do a face closeup on his evil side there's some weird lighting like when kids try to scare each other by holding a flashlight under their chins. I'm asking seriously, how do they do that? I can't imagine the actor holding a light source under his chin, and it seems ludicrous that someone would be crawling around on the floor doing the same. I don't really think it's special effects because back in 1966 those kind of speciall effects were pretty obvious. Any ideas, all you talented film making and watching types?