I have never had trouble with any actor being able to visualise things. They are amazing. As long as you have your monster head on a long stick, so you can hold it up there and you can wave it around and let them see it and explain it to them, they are just great.
And then you start getting into the technical side of it and the aesthetic side and with those areas you can come up with new ways to visualise things, new ways to render and use the computer to make things look different and new and stuff like that.