Lines of dialogue

STARLOG: Did you have someone speaking lines of dialogue while you were filming? BADHAM: Yes. While we were acting, the actors needed something to act to and the robot needed something to move to. It was very critical to have all of his parts on the set. and not say. "Oh, we'll just add that later." thereby putting actors in the terrible position of having to act to nothing else—like in special IX movies where the eight-armed serpent is not there. Here at least, you could literally develop scenes as you were going along and get interaction. You could get things that were bigger and better than things you had on paper because of that interaction of the actors and the robot just like you do with regular actors.
STARLOG: Other directors have sometimes said that they never believed that the "creature" in their movie was real. Did you believe that Number five was really one of your, actors?