Triggering a reaction in your reader

Continuing my recurrent theme of evoking reactions in your reader, I think that good writing is about triggers - words, phrases, images, places, sensations - that reach deep into the reader’s mind.

That reaction will be based on something the reader has actually experienced, or maybe something that the reader dreads ever having to experience. It is why horror and ghost stories work so well.
Yes, you are messing about with the reader’s head, yes, you may be forcing them to confront difficult truths, but isn’t that sometimes what writing is about?
If every story, every book, was about sugary-sweet people in lovely situations, then writing could never really move the reader as it should.
So, yes, writing can, on occasion, make the reader feel uneasy, uncomfortable, scared even, but, let’s be honest, isn’t that sometimes the way we feel in our daily lives anyway? It’s simply art reflecting reality.
John Dean