Dog training philosophies span from aversive-based methods, which rely on punishment and negative reinforcement, to reward-based techniques emphasizing positive reinforcement. In a large-scale behavioral and physiological assessment published in PLoS ONE, Ana Catarina Vieira de Castro and colleagues systematically compared these approaches to determine their effects on companion dog welfare.
The research involved 92 companion dogs recruited from seven training schools in Portugal—three that used reward-based methods, two that used mixed methods, and two that relied heavily on aversive techniques. Over three sessions, researchers collected video footage of behavior and saliva samples for cortisol analysis. They also evaluated dogs’ long-term emotional state through a cognitive bias task, a psychological measure of optimism or pessimism.
Dogs trained with aversive methods (Group Aversive) displayed significantly more stress-related behaviors—including lip licking, yawning, and panting—and were more frequently in tense and low behavioral states during training. Their cortisol levels rose sharply after training, confirming physiological stress. Moreover, these dogs showed a pessimistic cognitive bias, indicating that their negative emotional experiences extended beyond the training environment.
Even dogs trained under mixed methods—where aversive tools were used less frequently—showed elevated stress behaviors compared to dogs in the purely reward-based group. In contrast, dogs rewarded for correct behavior displayed relaxed body language, lower cortisol levels, and more optimistic responses in the cognitive bias task.
The findings confirm that aversive-based training compromises welfare not only during sessions but also afterward, affecting how dogs perceive their environment. Castro et al. conclude that consistent use of positive reinforcement fosters better emotional health, improves learning efficiency, and strengthens the human–dog bond. The results support global calls to eliminate punitive techniques from canine training and welfare practices.
Source: Castro, A. C. V., Fuchs, D., Morello, G. M., Pastur, S., Sousa, L., & Olsson, I. A. S. (2020). Does Training Method Matter? Evidence for the Negative Impact of Aversive-Based Methods on Companion Dog Welfare. PLoS ONE, 15. Published December 16, 2020.
