A study published in the journal Scientific Reports has discovered that dogs can experience negative emotions if they detect stress in humans through smell. It is already known that the scent emitted by a stressed individual can "subconsciously affect" the mental state of nearby people, influencing their emotions and decisions. The researchers aimed to determine if dogs are similarly impacted by the scents of stressed humans.
"Dog owners know how attuned their pets are to their emotions but here we show that even the odour of a stressed, unfamiliar human affects a dog's emotional state, perception of rewards and ability to learn," Nicola Rooney, a senior lecturer at the University of Bristol, UK, said.
"Working dog handlers often describe stress travelling down the lead, but we've also shown it can also travel through the air," Rooney, lead author of the study, said.
The team examined the impact of a stressed human on dogs' learning and emotional states, based on the idea that 'optimistic' or 'pessimistic' decisions reflect positive or negative emotions, respectively.
The researchers enlisted 18 pairs of dog owners to engage in a series of trials involving treats while being exposed to either no scents or odours from sweat and breath samples of stressed or relaxed individuals. During the trials, the dogs were trained to recognise that a food bowl in one specific location contained a treat, while another bowl in a different location was empty.
After understanding the distinction, the dogs were observed to move more quickly toward the food bowl containing a treat than the empty one. The researchers then examined how swiftly the dogs would approach "new, ambiguous" bowl locations placed between the original two.
A swift, brisk approach towards the food bowl reflected 'optimism' of finding a treat and thereby, a "positive emotional state," according to the authors. On the other hand, moving slowly towards the food bowl indicated 'pessimism' regarding finding a treat, thereby betraying the dog's negative emotions, they said.
The authors discovered that the scent of stress caused the dogs to be slower in approaching the food bowl placed in new locations, indicating a pessimistic attitude about finding a treat inside. However, dogs exposed to the scents of relaxed individuals did not exhibit this behaviour.
They said that the 'pessimistic' response reflected the dog's negative emotional state and could be the dog's way of conserving energy and avoiding disappointment.
"Understanding how human stress affects dogs' wellbeing is an important consideration for dogs in kennels and when training companion dogs and dogs for working roles such as assistance dogs," Rooney said.
(with PTI inputs)
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