a room as it slowly filled with fake smoke.[49] If they were alone, they
would generally respond; if they were with a group of studious actors,
they would continue to work, waiting for someone else to react.
Finally, we have the process of emotional amplification. People may
be more likely to adopt certain ideas or behaviours amid the intensity
of a social gathering: just think about the collective emotion that
comes with something like a wedding or a music concert.
The existence of complex contagions means we may need to re-
evaluate what makes innovations spread. Centola has suggested that
intuitive approaches for making things catch on may not work so well
if people need multiple prompts to adopt an idea. To get innovation to
spread in business, for example, it’s not enough to simply encourage
more interactions within an organisation. For complex contagions to
spread, interactions need to be clustered together in a way that
allows social reinforcement of ideas; people may be more likely to
adopt a new behaviour if they repeatedly see everyone in their team
doing it. However, organisations can’t be too cliquey, otherwise new
ideas won’t spread beyond a small group of people. There needs to
be a balance in the network of interactions: as well as having local
teams acting as incubators for ideas, there are benefits to having
Pixar-style overlaps between groups to get innovations out to a wider
audience.[50]
The science of social contagion has come a long way in the past
decade, but there is still much more to discover. Not least because it’s
often difficult to establish whether something is contagious in the first
place. In many cases, we can’t deliberately change people’s
behaviour, so we have to rely on observational data, as Christakis
and Fowler did with the Framingham study. However, there is another
approach emerging. Researchers are increasingly turning to ‘natural
experiments’ to examine social contagion.[51] Rather than imposing
behavioural change, they instead wait for nature to do it for them. For
example, a runner in Oregon might change their routine when the
weather is bad; if their friend in California changes their behaviour
too, it could suggest social contagion is responsible. When
researchers at MIT looked at data from digital fitness trackers, which
included a social network linking users, they found that the weather