To distinguish play from aggression in dogs, one can look for meta-signals (M), activity shifts (A), roll reversals (R), and self-handicapping (S).

“But typically what we can do then is look for what's referred to as Mars MS. So M being the meta signals. So those play boughs or in other species it will be other behaviors that are sort of indicating that I want to play. Uh I know chimpanzees have like 30 or 50 different meta signals for play. Um M A is for activity shift. So we will see different behaviors. They might be chasing, they might be pouncing, they might be wrestling, biting each other. Uh but you'll see these activity shifts and it's not in the same order as it would be if they were truly fighting. uh M A R R is for roll reversals. So you'll see that the the dog uh the dogs if they're of different sizes or different um sort of stamina or how big they are or how um competent fighters they are would be that they'll take turns winning and losing.”