It sounds strange but lets look at the most obvious case - exception - that proves my rule. Suppose you have a favorite author, who you love for style or content or storytelling ... whatever. He, she or it has written a new book, will you read it? Why? Because you don't know what the author has written, and it might be enjoyable. An author with a following plays on the knowledge gap to create interest in his or her new book. That's what advertising is for, to create your anxiety.
More generally, romance readers want to see how the heroine gets her man. Thriller readers want to know what mayhem the antagonist is creating, and how and if the protagonist can stop it. Mystery readers want to know who dunnit, and how the detective will figure it out. Students read textbooks for the same reason, a lack of specific knowledge.
As an author we must remember to focus on the goal of our work, to fill the audience's knowledge gap. That is why they came to us in the first place. That is knowing your audience.
So if we are smart authors, we will use our accumulated knowledge to create an interesting gap at the start of our book. The opening must be a tension filled hole, presented at least partially dug, worthy of the protagonist efforts to fill it, and mysterious enough to hold tension, and suspense to accompany the reader's anxiety. Although holes are always empty, our hole must be conveyed as real enough to allow our readers to identify with the situation and the characters, or if it is a fantasy, odd enough to be totally unreal. Not hard at all, this craft called writing.
The hook is really just a well dug, deep, complex hole that the rest of the book fills, shovel by interesting shovel. Each clod of dirt must hold the reader's attention, and therefore must be strewn with sparkling items - whether they are valuable or not is for the reader to decide.
The author's decision is whether the shovels should be sufficient to fill the hole completely for our readers, so that at the end of the novel they won't need a bridge to cross to the other side.
Modern writing and especially those authors who are trained in the superior MFA programs around the country, seem to think that filling the hole half-way and leaving the reader to climb down and walk across to climb up the far side is OK. They surmise that creates reader involvement. I like having the readers involved by watching the shoveling till the hole is level with the ground, and then they can walk to the other side with lower anxiety levels. But then maybe those well trained writers are not as obsessive as a retired surgeon.
That is my major tiff with well trained inconclusive writers, but that is for another day. Today we know why readers read what writers write, no gap in knowledge there.
