The Dynamics of Protest Recruitment through an Online Network

The recent wave of mobilizations in the Arab world and across Western countries has generated much discussion on how digital media is connected to the diffusion of protests. We examine that connection using data from the surge of mobilizations that took place in Spain in May 2011. We study recruitment patterns in the Twitter network and find evidence of social influence and complex contagion. We identify the network position of early participants (i.e. the leaders of the recruitment process) and of the users who acted as seeds of message cascades (i.e. the spreaders of information). We find that early participants cannot be characterized by a typical topological position but spreaders tend to me more central to the network. These findings shed light on the connection between online networks, social contagion, and collective dynamics, and offer an empirical test to the recruitment mechanisms theorized in formal models of collective action.

💡 Research Summary

The paper investigates how Twitter facilitated the rapid mobilization of the “Indignados” protests in Spain during May 2011. Using a 30‑day window (April 25–May 25) the authors collected 581,750 protest‑related tweets from 87,569 users and reconstructed both a directed “asymmetric” follower network and a reciprocal “symmetric” network. Activation time for each user is defined as the moment they first posted a protest tweet; once active, a user remains active for the rest of the observation period.

For every user the authors compute the proportion of followed neighbors that were already active at the moment of activation (kₐ/kᵢₙ). This ratio serves as an empirical analogue of the threshold parameter in classic diffusion models: a value near 0 indicates a “seed” who joins without peer pressure, while a value near 1 indicates a user who needs almost all of his/her contacts to be active before joining. The distribution of thresholds is roughly uniform across the interval