[Photo by Lang Congliu/China Daily]

Just like people, dogs get upset when their masters share their affection elsewhere, a new study finds.

Dogs can feel jealous if they think you pay more attention to other dogs, a new American study concludes.

Scientists generally view jealousy as an emotion requiring complex cognition, but some research suggests there may be a more basic form of jealousy, which evolved to protect social bonds from interlopers.

Some researchers predict that jealousy might even exist in other social species, like the cognitively sophisticated dog.

Since there had been no prior experiments on dog jealousy, researchers from University of California in San Diego modified a test used to assess jealousy in 6-month-old human infants.

Some 36 dogs were individually tested and videotaped while their owners ignored them in favor of a realistic-looking stuffed dog, a jack-o-lantern pail or a book.

The three tests were set up to test whether dogs' behaviors were indicative of jealousy or a more general negative effect due to the loss of the owner's attention. The dogs' behavior was then analyzed for aggression, attention seeking and interest in the owner or object.

The researchers found that dogs were about twice as likely to push or touch the owner when the owner was interacting with the faux dog (78 percent) as when the owner was attending to the pail (42 percent). Fewer (22 percent) did this when a book commanded the owners' attention.