University of Sydney researchers have discovered how to tell whether a dog is pessimistic or optimistic, an ability they say holds some practical applications for canine welfare and training.

In the study published in PLOS One, researchers taught participating dogs to touch a target after hearing a tone associated with a lactose-free milk reward, and to abstain from touching the target after a tone associated with water. The dogs were then exposed to ambiguous sounds, and if they responded to the sounds researchers classified them as optimistic because they were more hopeful that they would receive a treat.

Pessimistic dogs appeared stressed because responding to the ambiguous tone did not result in a milk reward, and they tended to stop responding to the sounds more quickly, the study revealed.

Measuring whether dogs are more pessimistic or optimistic can help to determine which dogs are suitable for certain work roles, said study author Melissa Starling, Ph.D., from the university's Faculty of Veterinary Science.

"This research could help working dog trainers select dogs best suited to working roles," Starling said. "If we knew how optimistic or pessimistic the best candidates for a working role are, we could test dogs' optimism early and identify good candidates for training for that role. A pessimistic dog that avoids risks would be better as a guide dog while an optimistic, persistent dog would be more suited to detecting drugs or explosives."

Starling also reported in her study that measuring a dog's mood could lead to more accurate welfare assessments by placing value on positive, pleasurable activities for dogs, instead of only focusing on avoiding pain and suffering.