The Internet has been ascribed a prominent role in collective action, particularly with widespread use of social media. But most mobilisations fail. We investigate the characteristics of those few mobilisations that succeed and hypothesise that the presence of ‘starters’ with low thresholds for joining will determine whether a mobilisation achieves success, as suggested by threshold models. We use experimental data from public good games to identify personality types associated with willingness to start in collective action.

Presented by Helen Margetts and Peter John at the European Consortium of Political Research (ECPR) general conference in Rejkavik on 26 August 2011.

Political scientists and economists commonly test for different kinds of social influence on collective action, particularly social pressure (visibility) and social information about the contributions of others (leading to conditional cooperation) but rarely in the same study design. This paper assesses the relative effect of these two kinds of social influence suggesting that their impact is best understood through hypothesizing for heterogeneous treatment effects based on personality.

This paper tests the hypothesis that social information provided by the internet makes it possible in large groups to exert social pressure that Olson considered viable only for smaller groups. In two experiments - laboratory and field - subjects could choose to sign petitions and donate money to support causes. Participants were randomised into treatment groups that received varying information about how many other people had participated and control groups receiving no social information.