Dogs trained using aversive stimuli, which involve punishments for incorrect behavior, show evidence of higher stress levels compared to dogs trained with reward-based methods, according to research out of Portugal.
Researchers from the Universidade do Porto observed the behaviour of 92 companion dogs from seven dog training schools in Portugal that use either aversive methods, reward methods or a combination of both. They filmed training sessions and tested saliva samples for the stress-related hormone cortisol.
The study—which is published in PLOS ONE—found that dogs trained using aversive and mixed methods displayed more stress-related behaviours, such as crouching and yelping, and showed greater increases in cortisol levels after training than dogs trained with rewards.
The authors also conducted a cognitive bias test in an unfamiliar location outside of the dog’s usual training environment with 79 of the dogs, to measure their underlying emotional state.
They found that dogs from schools using aversive methods responded more pessimistically to ambiguous situations compared with dogs receiving mixed- or reward-based training.
Previous survey-based studies and anecdotal evidence has suggested that punishment-based training techniques may reduce animal welfare, but the authors state that this study is the first systematic investigation of how different training methods influence welfare both during training and in other contexts. They say that these results suggest that aversive training techniques may compromise animal welfare, especially when used at high frequency.