Shock Collars May Make Dogs More Pessimistic
In the past few decades, dog trainers have overwhelmingly switched to practicing and recommending reward-based training for dogs rather than aversive training. Rewarding your pooch with treats, toys, or attention when they behave well and denying those things when they don't seems to be more effective and salubrious instead of employing aversive methods like spraying water, yanking on their leash, or using a shock collar to punish unwanted behaviors. Scientific studies are now providing empirical evidence in favor of reward-based training.
Complementing those findings is a new study published to the journal Scientific Reports. A group of canine researchers and veterinarians primarily based in the United Kingdom discovered that dogs trained with aversive methods may have a more negative, pessimistic mood.
Lead author Rachel A. Casey and her colleagues recruited 100 dogs for their study. Fifty of the canines had experienced two or more aversive training methods in the past, such as physical punishment, an electronic shock collar, a water sprayer, a choke collar, or a loud sound-based distraction device. The other fifty had undergone only reward-based training. Dogs in the aversive and reward group were matched based on breed, age, neuter status, and gender.
Next, all of the dogs were identically trained that a bowl placed on the left side of a test arena would always contain a treat, while a bowl placed on the right side would not. Eventually, they all ran much faster to a bowl placed on the left side rather than the right, realizing that there would almost certainly be a treat in a bowl on the left side.
Now the real experiment could begin. The researchers placed a bowl in an ambiguous location (somewhere in the middle of the room) and compared how fast it took each dog from the reward-trained and aversive-trained groups to run to it.
"Latency to move to the bowl in these trials was used as an indicator of whether the dog anticipated food to be present (short latency—positive (‘optimistic’) interpretation of ambiguity inferred to reflect relatively positive affect) or absent (longer latency—negative (‘pessimistic’) interpretation of ambiguity inferred to indicate a relatively negative affective state)," the authors explained.
They found that dogs trained without aversive methods ran faster to the bowls regardless of where they were placed, as if they were more optimistic that a treat would be present.
"This ‘pessimistic’ bias indicates that dogs which have been exposed to more aversive training methods have a decreased expectation of reward than those which have not experienced these methods," the authors wrote. "This may reflect a negatively biased processing of ambiguous information, as is found in depressed people, rats exposed to chronic psychosocial stress, and in a variety of other judgement bias studies involving animals in putative negative affective states."
This explanation might be a bit of a stretch. It could simply be that dogs extensively trained with treats might be more on the lookout for them. However, the authors note that owners in both groups reported using reward-based methods to train their dogs (e.g. praise, play and food treats) as it is difficult to find owners who do not use any such methods with their dog. So it wasn't just that the dogs in the aversive group never received rewards, but that they also received aversion-based training.
"Because of the potential welfare implications of using two or more punishment-based techniques identified in this paper, we believe that professionals should advise owners to use the least aversive methods available to them to modify their dog’s behaviour," the researchers concluded.
Source: Casey, R.A., Naj-Oleari, M., Campbell, S. et al. Dogs are more pessimistic if their owners use two or more aversive training methods. Sci Rep 11, 19023 (2021). https://doi.org/10.1038/s41598-021-97743-0