Dogs communicate with their tails in ways that are more complex than people thought even a few years ago, and new studies continue to reveal more about the information that tails convey. Many people have wondered whether dogs with docked tails or naturally short tails are less able to communicate than dogs whose tails are long and have not been docked.
Nearly 500 dogs were videotaped when approaching a life-sized robot dog that had either a short tail or a long tail and the tail was either wagging or held still. They noted whether the dogs were hesitant in their approach to the robot dog or if they approached without such caution.
What did they find? They found that dogs were more likely to approach, without hesitating, a robot with a long wagging tail than one with a long tail that was held still. They were equally likely to approach without caution a short tail when it was still and when it was wagging. Approaches to the short tail (whether wagging or still) were more likely to be hesitant than approaches to a long wagging tail, but less likely to be hesitant than those to a long tail that was still.
The experimenters concluded that it is harder to convey information with a short tail than with a long tail. One possibility is that it is harder for dogs to obtain information from a shorter tail than from a longer tail.
I think the coolest part of this study is the use of a robot dog in the experiment. If live dogs had been used, studying the effects of tail length would have been challenging because so many other variables could have clouded the issue. With a robot, the “dog” is in the same posture, smells the same, and is not adding additional behavior into the experimental design. The different responses by approaching dogs can be explained by the only parts of the robot that are different—tail size and tail motion.