There are several reasons why that advice is wrong, here’s one of them: Fear is designed to be aversive, that’s why it is an effective way of affecting behavior and keeping animals out of trouble when they encounter something that might hurt them. Fear is aversive enough that no amount of petting or sweet talk is going to make your dog more likely to shiver and shake when she hears thunder rolling as the clouds billow and the rains begin.

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. The fact is, it is almost impossible to “reinforce fear.” Fear is highly aversive, and if anything, it works in reverse. I suppose, if you did it often enough, you could create an association between thunder and petting that would make your dog afraid of petting, but it is extremely unlikely to go the other way around.

It is true that you can make your dog more afraid than he already is, by doing something yourself that scares him, by forcing him into situations that scare him already or by being afraid yourself. Emotions are contagious, so if you want your dog to be afraid of thunder, then be afraid yourself! But you’re not going to make him more afraid of storms if you stroke his head and tell him it’s going to be okay.