Guess what? Your dog knows its left from its right. At least, when it comes to the way it wags its tail. And it may not be the secret dog messages you might suspect occurs when dogs meet each other.  Tail-wagging is one of the most common (not to mention heartwarming and smile-inducing and ) things our dogs do all the time. But did you know that even the simplest behaviors may have unexpected meanings?

Here are 4 common canine habits and what they may mean.

1. Wag This Way 

In a 2007 study by Giorgio Vallortigara, PhD, of the University of Trento, 30 dogs were introduced to a series of visual stimuli in a controlled environment. These images ranged from positive (the dog’s owner, for example) to negative (an unknown dominant male dog). The study found that a wag to the right was a reaction to something positive, while a wag to the left indicated an anxious, uncertain or negative emotion. In addition, a dog that saw another dog wag one way would often respond to that behavior and wag the same way. You can read all about the study, which was  published in Current Biology,