The Ideal Reader

I just read a book called On Writing, and it had an interesting concept I thought I'd talk about: The Ideal Reader.
The Ideal Reader is basically the person you write for.
In the book, the author's Ideal Reader was his wife - who always critiqued his books. When writes, he thinks about what scenes would make her laugh, and how she'd act to certain parts.
The nice thing about the Ideal Reader is that it gives you a specific goal. If you write with the sense of "how will the world react to this passage," you probably won't get a solid reaction. Everyone will react differently, both positively and negatively. For the Ideal Reader, you get a very definite answer for if something works or not, and what you might do to fix it.
And if you have a good Ideal Reader, then a lot of other people will also like the final result.

I don't know who my Ideal Reader would be. Perhaps I'll meet one. Or maybe I'll make one in my head.
This isn't something that I've tried out myself, but it sounds intriguing. I'm sure it won't work for everyone. But it certainly worked for this writer, and you can't argue with his success: Stephen King.