The ability on a camera-laden set to inhabit a character without a twitch of distraction or preoccupation or visible hint of the internally or externally irrelevant is a scary but brilliant feat.
Ordinary people cannot do it. But I have seen great actors do it even at cocktail receptions full of cell phones. In a world where major writers have announced that they cannot focus on their work without extracting or blocking the modems in their laptops, this kind of thespian concentration is worth noting. (One thinks of the writer Anne Lamott’s remark on her own maturing undistractibility: “I used to not be able to work if there were dishes in the sink,” she has said. “Then I had a child and now I can work if there is a corpse in the sink.”)