There’s a reason crooning “good dog!” makes your pup light up — and it’s not just because you often follow that phrase with a treat. Multiple studies show that dogs can not only read facial cues but can understand human speech, a concept that’s both good and bad for people. Sure, they can understand when you’re saying nice things but this means they’re equally capable — and, according to a new study, affected — when you’re saying not nice ones.
The study, published in BioRxiv last month, found evidence that training dogs using negative commands can “compromise the welfare” of pets, causing them long-term stress and lowering their overall cognitive abilities.
In the study, researchers analyzed the short-term and long-term wellbeing of 92 different dogs from seven different training facilities in Portugal. The most common breed among the group was sheepdogs followed by pinschers, schnauzer, terriers, scent hounds, retrievers and water dogs. More than half of the dogs were male and roughly one third were neutered.
The dogs were divided into two different groups based on how the owners had chosen to discipline them. The “aversive” group was made up of the dogs that were being trained through things like choke collars, spray corrections, and acting in a threatening manner (by yelling or confronting the dog). The “reward” group consisted of the dogs who were being trained using positive reinforcement like treats.
Over the course of three years, the researchers performed a series of different tests on the dogs — before and after training sessions — to measure their levels of stress. The tests were conducted both in-person and through videos and included looking at things like saliva samples (to measure cortisol levels), stress-related behaviors (such as lip-licking) and judging the overall behavior of the dog.
In one step, dogs were brought in a month after training and introduced to two different food bowls, one of which had a sausage; the other of which didn’t. The researchers noticed that the dogs who had been trained with negative commands approached the bowls much more slowly than the dogs trained with positive commands, suggesting an overall “pessimism” in that group.
Overall, the results showed that dogs who were subjected to intimidating behavior and commands were more likely to carry stress in the longterm. “Our results show that companion dogs trained using aversive-based methods experienced poorer welfare as compared to companion dogs trained using reward-based methods, at both the short- and the long-term level,” the researchers conclude. “Specifically, dogs attending schools using aversive-based methods displayed more stress-related behaviors and body postures during training, [and] higher elevations in cortisol levels after training.”
The researchers say that it’s the first “comprehensive and systematic” study to measure how dog training affects welfare. Given the reactions to it, it’s unlikely to be the last.
Read more from Yahoo Lifestyle: