Here’s the example for you of how hard it is to “reinforce” fear. What if someone tried break into your home in the middle of the night? Let’s say they did, and after the intruder left, a friend or loved one sat down with you on the couch, brought you tea and gave you a hug. Would the tea and sympathy make you more likely to be afraid if it happened again the next night? Of course not.
Can you imagine someone saying: “Well, I understand that you are frightened, but I’m going to ignore you because any sympathy that I would give you might make you more likely to be frightened if it ever happens again.” I don’t know about you, but that would be my EX friend.
One could criticize this example as one of misplaced anthropomorphism, but the fact is that this process works much the same in dogs as it does in people.
I know that you post lots of good information on here, and I am certainly not an expert on dogs. I _can_ speak to this, however, from the perspective of a mother... of two boys, one of whom was naturally pretty bold as a young child, the other of whom was naturally hyper-reactive. With the bold one, if he seemed to need sympathy (which he rarely did because he bounced back easily) I could give him hugs and kisses, sympathize and he'd happily go off with his new band-aid. The younger, hyper-reactive one was a different story. I couldn't give him much sympathy at all. If he fell and cried, I would check him over to make sure he didn't have any real damage, then tell him, "you're fine!" with a smile on my face and send him off. Any sympathy at all, and he'd ramp up into hysterics. (and, incidentally, he threw himself on the floor screaming in terror at thunderstorms until he was at least 4 or 5)
Both my kids had serious health problems when they were little, and I learned very quickly what worked best for each of them, to keep them on an even keel under painful and frightening hospital experiences. The hyper-reactive toddler/young child has grown into a mid-teen who is still sensitive but is much more resilient, while my Steady-Eddie son is still the same.<g> While not making a big deal of a frightening incident, or "marking" it with too much external emotion may not make it "less frightening" the next time, it certainly can keep it from getting blown out of proportion so that it "feels" bigger than it was in hindsight.
I have to bow to the experience of others when it come to dogs and puppies. But after raising my own children, and training many horses over a period of almost 35 years I can tell you this is true of both those two species. Everything I know about raising kids, I learned from training horses - Be fair, be firm, love them lots and remember that each one is an individual.