Dogs are universally renowned as sunny, tail-wagging optimists- but do all dogs share this trait?

A University of Sydney study recently showed that dogs can have an ingrained pessimistic or optimistic nature that can be determined through a series of tests. Researchers conducted detailed experiments which determined that some dogs are naturally pessimistic and others have a more optimistic nature.

The comprehensive study utilized 40 dogs of all ages and breeds. The dogs were each trained to place their paws on a target to receive either milk or water. The targets were equipped with distinct tones two octaves apart. One tone indicated a reward of milk; another indicated plain water. Then the dogs were provided with ambiguous tones that fell between the milk and water spectrums. Optimistic dogs pressed the ambiguous tone targets hoping for milk; pessimistic dogs did not.

This personality test could be utilized for determining which dogs are best equipped to be service dogs. Pessimistic dogs, who are naturally cautious, would be better for guiding blind or disabled persons. Optimistic dogs would be better suited for search-and-rescue missions where their optimism would be useful for persistently trying to find survivors.

Not all scientists agree with the outcome of the study. Mark Bekoff, professor emeritus at the University of Colorado, disagreed with the findings. “Maybe they just gave up,” he said, indicating that the “pessimistic” dogs were just realists who concluded that the treat of milk was not forthcoming when the ambiguous tones were sounded.

However, the study does conclude that dogs have distinct personality traits that can be measured and tested. “Especially in dogs who are abused early on, you definitely see animals who just really won’t work that hard to get love or affection, having failed before,” Bekoff said. “I think it’s perfectly legitimate to say that there are optimistic and pessimistic dogs —  and that you can change their behavior.”