You should read the original short story by Richard Matheson entitled "Prey", the movie version is tame by comparison.
All three stories in this movie were based upon short stories by Mr. Matheson, but he only wrote the screenplay for the attacking doll one. The DVD contains a "special feature" interview with him and he said he knew that story would be the clincher and he wanted to keep it for himself. Ms. Black said in the commentary portion that she made up some of the dialogue she used on the phone calls in that segment to help her flesh out her character and she said the idea for her character's final, unforgettable transformation in the end was her idea.
Very cool. The first Matheson novel I read was "Bid Time Return", I think it was about a year after the adaptation "Somewhere In Time" was released. I was like 12 at the time, I loved the time travel angle to the movie and picked up the novel at the library. Then I started noticing his name in the credits for Twilight Zone episodes and sci-fi/horror films and I bought a couple short story collections. I've been a fan ever since, he's one of my all-time favorites. He had an impressive career.