Many myself included believe that the trigger for a protection dog to engage a threat is defense ie the dog feels pressure, and is genetically predisposed and/or trained to react to pressure with aggression. This is definitely true for some dogs.
Does anyone think that an effective trigger can be prey? It occurred to me because my male rott is hard wired to go after any fast movement. An aggressive person's movements are fast and strong, and will definitely trigger the dog's prey drive/interest. Where it goes from there is another story, but in this case prey was what drew the dog's attention not any kind of pressure. Thoughts?