Charlie Brown, a spaniel, loses focus under pressure in study.

If you’re hyper by nature, stress can sometimes send you over the edge. But if you’re known for being laid-back, stress often offers that extra edge.

It appears the same thing happens with dogs, a new study suggests.

The study, published on July 14 in Animal Cognition, found that a little extra stress and stimulation makes hyper dogs crack under pressure but gives mellow dogs an edge.

Researchers were from the University of Pennsylvania, Duke University, and the University of Arizona.  

In a series of experiments, the researchers challenged dogs to retrieve a meat jerky treat from a person standing behind a clear plastic barrier. To get it right, the dogs had to resist the impulse to try to take the shortest path to reach the treat—which would only cause them to whack into the barrier and bump their heads against the plastic—and instead walk around the barrier to one of the open sides.

In one set of trials, an experimenter stood behind the barrier holding a treat and called the dog’s name in a calm, flat voice. In another set of trials, the experimenter enthusiastically waved the treat in the air and used an urgent, excited voice. (See the YouTube video above.)

The researchers studied video recordings of each dog (3 pet dogs and 76 service dogs) and estimated their baseline temperament in terms of tail wags per minute.

“The service dogs were generally more cool in the face of stress or distraction, whereas the pet dogs tended to be more excitable and high-strung,” researcher Emily E. Bray, MA, said.

Both groups of dogs were able to solve the puzzle. But the optimal amount of stress and stimulation depended on each dog’s disposition.

For the dogs that were naturally calm and laid-back—measured by how quickly they wagged their tails—increasing the level of excitement and urgency boosted their ability to stay on task and get the treat.

For excitable dogs, the pattern was reversed. Increasing the level of stimulation only made them take longer.