http://www.sciencemag.org/news/2019/11/bad-dog-think-twice-yelling-experts-say

Punishing your dog to discourage bad behavior could make them more stressed and “pessimistic,” a new study finds.

Few things are more adorable—or destructive—than a new puppy. When they pee on rugs, chew furniture, and get aggressive with other pups, their stressed-out owners usually turn to dog training. Now, a novel study suggests programs that use even relatively mild punishments like yelling and leash-jerking can stress dogs out, making them more “pessimistic” than dogs that experience reward-based training.