Naturalistic horror movies

There are a few films that I was thinking about as totally naturalistic horror movies, but would that be a fair way to title some of them? The ones that come to mind are: Straw Dogs Targets (1968) The Incident (1967) Texas Chainsaw Massacre In Cold Blood See No Evil Last House on the Left Martin My question is: would you consider Straw Dogs or Targets horror films? If not, what makes TCM horror and Straw Dogs "thriller" or "suspense" or what not? All of these movies have moments that make me feel dread and/or fear in a very similar way. But is the difference, if any, in the amount of violence or violent acts on screen? And on a side note, does the lack of supernatural elements make a movie less as horror movie for you?