Complex Contagions

Posted on Nov 23, 2020

I read this interesting paper the other day about so-called ‘complex contagions’.

Let us consider a simple contagion first. A simple contagion, such as a virus, can spread from a single interaction with a host. This concept can also be brought to bear when thinking about how new ideas or information spread. For example, the knowing score of a sports game might spread like a simple contagion. It requires just one interaction, me teling you the score, to spread.

A complex contagion requires many sources of ‘activation’ to spread. An example of a complex contagion may be the adoption of some new fashion. If person A sees person B wearing a bowler hat, they are unlikely to immediately adopt bowler hats. Yet, if they also see persons C, D, E and F wearing bowler hats, then they are much more likely to do so.

Many collective behaviors also spread through social contact, but when these behaviors are costly, risky, or controversial, the willingness to participate may require independent affirmation or reinforcement from multiple sources. We call these “complex contagions” because successful transmission depends upon interaction with multiple carriers.

I think this is an interesting thing to think about when trying to effect change in an organisation. Let’s take, for example, adopting type-checking for Ruby. As Ruby is not traditionally type checked, this could be considered a ‘controversial’ change. Thus, effecting this type of change looks more like spreading a complex contagion.

With this in mind, we can start thinking about our multiple points of activation. You could, for example, convince key people to also spread your message, or share articles in Slack promoting the benefits of type checking. Making the distinction between simple and complex contagions allows us to think about how to most effectively spread our change.