“Contagious” Behavior in Dogs?

All of us who have been around dogs have encountered the following:

• The dog down the street begins to bark at who knows what, and within seconds, every other dog within hearing is barking his head off as well;
• Two dogs begin to play chase at the local dog park and soon half a dozen dogs are drawn into the game;
• One of your dogs turns his nose up at the food dish and walks away, but comes back and eats like he is starved when your other dog starts to eat.

What’s going on here? Isn’t it just dogs being dogs?  Well, yes, all of this is normal behavior for dogs but the behavior is common in a variety of other social animals as well.

This phenomenon of one animal doing something that draws others into doing the same thing is called social facilitation.  Some have referred to it as social contagion in animals.  It is seen mainly in highly social animals.

It’s been seen in the feeding of chickens, grooming behavior of rhesus monkeys and athletic performances in people, among others.  The functions are not well understood, but it probably has several.

One is that it may allow animals to take advantages of resources that are scattered in patches, such as seeds on the ground.  One chicken discovers them and starts to feed, and it draws the other members of the flock to feed as well.

It probably also leads to coordination of cooperative activities such as hunting or protecting the group against intruders.  The “bark fests” that dogs get into could have evolved in this way to intimidate and chase off two-legged as well as four-legged intruders.

The social howling of wolf packs may alert other packs to their presence in the area and advertize their possession of a territory.

A particularly dangerous situation where social facilitation can occur is in aggressive or predatory attacks on people or other animals.  Some of the most savage attacks by dogs on people and other animals have involved groups of dogs.  In some cases it appears to be motivated by predation, because there was feeding on the victim, in other cases it appears not to be motivate by predation.

In a few cases it has been shown that the dogs involved in the attacks were not particularly aggressive until aroused by the presence of other dogs.  The aggression seems to be contagious – such as the hysteria experienced by groups of fearful people.  The dogs do things in groups that they wouldn’t do by themselves.

The possibility of such socially facilitated aggression provides a good reason not to let dogs roam freely in groups.  One aggressive dog could incite others to join in, creating a much more dangerous situation than just a single aggressive dog.

Not all dog behavior is socially facilitated.  Fears of thunderstorms and other loud noises and separation anxiety do not seem to be spread from one dog to another.  Furthermore, not all dogs engage in socially facilitated barking, feeding, play or aggression.  Some dogs just don’t join in the “bark fests;” others don’t join in to group aggression.

We don’t know why these differences exist and what factors predispose some dogs to engage in socially facilitated behavior and others not so much.  It is likely that the prior experiences of a dog influence the occurrence of social facilitation.

Dogs that have joined in group behavior in the past and have been rewarded in some way are likely to do it again.  It is possible that just the act of joining in to group activities, even if the participants don’t get other primary reinforcers such as food, sex or play, may be rewarding for some dogs.

The next time you hear a group of dogs begin to bark or howl in response to one another, keep in mind that it isn’t much different than groups of fans being “egged on” by others screaming for their favorite teams at a sporting event.