Did you ever get the feeling your dog was laughing at you? New research suggests maybe he was! Dogs make "huffing" noises scientists think is doggie laughter.

Dogs make that noise when inviting another animal—or a person—to play. They also make it when tossing a toy around by themselves.

Patricia Simonet, a Spokane, Washington, psychologist, first identified the sound. She recorded various dog sounds on a special machine that also graphs noise. The dog laughs looked different. When she played the sounds back to other dogs, they also reacted differently.

Some pups acted afraid when they heard growls, whines, or barks. But, says Simonet, "All the dogs responded positively to the laugh." They began to play. Gorillas, chimps, orangutans, and rats are also known to laugh. Does laughter mean sense of humor? No one knows for sure yet, but researchers are working to answer the question. Check out these seven stories and decide for yourself if the animals' antics mean they find things funny!

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