Connection found between emotion and direction of dog's tail wagging
Emotional connection found between the feelings of animals and side the tail moves
Dogs can tell how other dogs are feeling from the particular ways their tails are wagging, according to researchers who monitored the animals' heart rate as they watched canine movies.
The Italian team found that dogs had higher heart rates and became more anxious when they saw others wag their tails more to the left, but not when they wagged more to the right, or failed to wag at all.
The curious form of communication is probably not intentional, or consciously understood, but is instead an automatic behaviour that arises from the structure of the brain, said Giorgio Vallortigara, director of the animal cognition and neuroscience laboratory at the University of Trento.
"It's not something they explicitly understand," Vallotigara said. "It's just something that happens to them."
Vallotigara traces the effect back to the way the two halves of the brain process different experiences.
In a previous study, his team showed that when a dog had a positive encounter, such as seeing its owner, activity rose in the left side of the brain, which brought about more tail wagging to the right. A negative experience, such as being confronted by an aggressive and unfamiliar dog triggered greater activity in the right side of the brain, and more tail wagging to the left.
The effect is barely visible because dogs wag their tails too fast, but it can be seen with slow motion video, or in larger breeds that wag their tails with less gusto.