Many pet owners believe their four-legged friends have distinct personalities, and now scientists have some proof.

Researchers use animals to model disease but emotional traits and personality are seen as uniquely human, a result of genetic and environmental factors.

Pets may seem like they have personalities, but conventional wisdom says pet owners project their own personalities onto their animals.

To test canine character, psychology Prof. Samuel Gosling at the University of Texas and his colleagues studied 78 dogs and their owners at a dog park in Berkeley, Calif.

Dog owners were asked to rate themselves and their pooches on four different personality traits: energy, affection, anxiety and intelligence.

Each trait was defined by characteristics. For example, being "curious about many different things" was considered a mark of intelligence.

The researchers also tested how well the owners' ratings matched the dogs' behaviour in field tests, such as their ability to find a dog biscuit placed under a plastic cup.

Strangers also watched the animals perform the tasks and rated the pets to check if the owners' judged their pets accurately. In general, owners and strangers agreed on a dog's personality, which suggests personalities are real, says Gosling.

The researchers found personalities vary widely within a breed, meaning stereotypes such as all pit bulls are aggressive or all beagles are intelligent don't hold up.

Animal behaviour experts call the study thorough, but note Gosling relied on subjective definitions of personality traits.

He hopes to develop the research using more objective measures to select service dog candidates. The idea is to assess a dog's personality to see if it is suited to work as a Seeing Eye dog or police dog.

The study appears in the December 2003 issue of the Journal of Personality and Social Psychology.