A new study shows that dogs can be optimists or pessimists, just like humans.

Does your dog think the water dish is half empty? New research from the University of Sydney shows evidence that dogs can be distinctly optimistic or pessimistic. Just like humans, optimistic canines have a distinctly sunnier outlook on life, while pessimistic pups are likely to expect the worst.

The dogs were trained to touch a target after hearing one of two tones — two octaves apart — to receive a drink. One tone meant they’d receive milk, a reward, while the other just meant they’d get water. Once they’d learned what those tones meant, they were presented with new tones in-between the “milk” and “water” pitch.

If a dog kept happily hitting the target through these ambiguous tones, the researchers claim, it’s probably because it was hopeful that one of them would lead to a reward. On the other hand, the researchers report, the “pessimistic” dogs grew distressed when ambiguous tones didn’t result in milk, and avoided repeating the task.

This study is really meant as a proof-of-concept for a sort of doggy personality test– one that could help determine the best service dogs for particular tasks. The researchers found that pessimistic dogs, for instance, were doing better in their training to be guide animals for the disabled. They were careful and anxious about taking risks. But a persistent, optimistic dog might do a better job in search-and-rescue missions.