One of my favorite books on the craft of writing is THE STORY BOOK by David Baboulene. He explores the concept of knowledge gaps a great deal. I'd love to quote all of the text here for you, but that's probably not legal. BUY THE BOOK, if you don't already have it. Here is a snippet:
"When we have a gap in knowledge we set about understanding and filling it, and until we have the correct information to fill the gap, we try out different possibilities to see which ones might fit. We project different answers into the gap, and when we find one that seems right, we use it and build on it to project further. And this is how we create an underlying story, a subtextual story in our own minds, all by ourselves. ... Our brains instinctively do this; ... so the writer uses this to his advantage. He grips the audience and maintains interest by constantly cracking open gaps in the knowledge held by different participants and crucially, that available to the audience. Sometimes the audience has more knowledge than the protagonist, sometimes less. Sometimes the audience has the same knowledge as the protagonist, but less or more than another player. ... In a good story there is always, always a difference in the knowledge possessed by at least one participant when compared to the audience" (THE STORY BOOK, p.77).
Another book I recently read (written by Deborah Halverson) addressed the same topic, specifically regarding dialogue:
"Tease readers with bits. Give readers part of the facts in the dialogue but not all of them. ... Dialogue is a great venue for sprinkling. You can make readers wonder about what you've left out to entice them to stick with the story" (WRITING YOUNG ADULT FICTION FOR DUMMIES, p.179).
Do you intentionally use knowledge gaps when writing your fiction?