It’s called the collective action problem: we’d rather rely on others to do the hard work.

In a cohesive community however, it is more likely that people will volunteer to become active. The reason? The enforceable trust that comes with the cohesion.

This is important for how you organise your daily working life (make sure your team is cohesive) 🙂 but may also explain why some communities have less trouble than others to overcome disaster experiences.

Social capital is an upcoming concept in the traumatic stress area, and a very interesting one. Last month, Prof. Ichiro Kawachi (Harvard University) gave a one hour crash course in the Netherlands. Some of the things (I think) I have learned are below.

To start with a definition, social capital refers to the resources that people derive from their membership in social networks. There are two important schools of thought:

The Social Cohesion school focuses on the central role of trust. Trust originates in ‘network closure’: if Mike defaults on his loan to a friend, it will risk damaging his reputation and no one will want to lend him anything in the future. The costs of free riding are high when there is a high level of cohesion.

The Network school focuses on network heterogeneity and ‘upper reachability’. It tells you how easily you can attract resources (e.g. if your toilet is broken, do you know someone who can repair it? ) and/or reach out to people in positions of influence.

While the Network school looks predominantly at the availability of resources in the network to the individual, the Social Cohesion school is interested in characteristics of the group. Prof. Kawachi sees networks as more than their individual elements. They provide a) things for the individual: information, emotional support and b) things for the network as a whole: social influence, informal social control, collective efficacy.

Strong examples of how far the influence of networks reach come from research by Christakis and colleagues. They showed that smoking cessation, obesity, and happiness are contagious: people’s individual social influence can spread about three degrees of separation before it fades out (the three degrees of influence rule: behavior can impact the ‘friends of ones friends’ friends’).

Social capital is tricky to investigate, due to issues with shared method variance (asking people to self-report about their social capital and outcomes), reverse causation (social capital may lead to health, but it could also be vice versa) and confounding problems (a shared factor, e.g. the physical environment, may be the actual cause of the effect).

Some of these issues can be overcome with longitudinal studies that obtain data from various sources and use (alternative) randomization approaches. One of the study sites of a healthy aging study by Kawachi and his colleagues was very close to the 2011 earthquake epicenter. They had collected baseline data in 2010 and are currently conducting a follow-up study; an accidental natural experiment. The hypothesis is that residents living in neighborhoods with higher levels of social capital will experience faster recovery.

If you would like to read more on social capital before the Japanese results become available, Kawachi’s recent book Global Perspectives on Social Capital and Health looks like a great start. These papers may also be of interest:

• Christakis, & Fowler (2007). The Spread of Obesity in a Large Social Network over 32 Years. N Engl J Med, 370-379 DOI: 10.1056/NEJMsa066082

• Kawachi I, & Subramanian SV (2006). Measuring and modeling the social and geographic context of trauma: a multilevel modeling approach. Journal of traumatic stress, 19, 195-203 PMID: 16612828