Protests as Strategic Games: Experimental Evidence from Hong Kong's Antiauthoritarian Movement*
Social scientists have long viewed the decision to protest as strategic, with an individual's participation a function of their beliefs about others’ turnout. We conduct a framed field experiment that recalibrates individuals’ beliefs about others’ protest participation, in the context of Hong Kong's ongoing antiauthoritarian movement. We elicit subjects’ planned participation in an upcoming protest and their prior beliefs about others’ participation, in an incentivized manner. One day before the protest, we randomly provide a subset of subjects with truthful information about others’ protest plans and elicit posterior beliefs about protest turnout, again in an incentivized manner. After the protest, we elicit subjects’ actual participation. This allows us to identify the causal effects of positively and negatively updated beliefs about others’ protest participation on subjects’ own turnout. In contrast with the assumptions of many recent models of protest participation, we consistently find evidence of strategic substitutability. We provide guidance regarding plausible sources of strategic substitutability that can be incorporated into theoretical models of protests.
In this article, we identify the causal effect of beliefs about other individuals’ protest turnout on one's own, conducting a framed field experiment with potential participants in an antiauthoritarian protest in Hong Kong. We study participation in a July 1 march, a yearly protest that represents an important component of Hong Kong's ongoing antiauthoritarian movement, epitomized by the recent Umbrella Revolution.2 The July 1 march shares many essential characteristics with antiauthoritarian protests across time and space: participants aim to achieve policy concessions from an authoritarian regime by turning out in large numbers, facing the threat of government crackdown. In this context, we experimentally recalibrate individuals’ beliefs about others’ protest participation and study how these beliefs affect one's participation. We find consistent evidence of strategic substitutability in the decision to protest, challenging many recent models of protest participation that assume strategic complementarity.
Second, even when measured in real time, it is extremely difficult to exploit variation in beliefs to identify causal effects. Naturally occurring variation is very likely to be endogenous with respect to behaviors of interest. Experimental variation, for example, arising from an information treatment, runs into challenges from heterogeneous priors, which imply that the same information treatment can generate positive belief updating among one subset of the sample (i.e., those whose priors are below the information provided) and negative updating among another subset.4 This means, for example, that even an effective intervention may produce average treatment effects on beliefs or behavior that spuriously appear to be null results. The average effects would simply reflect offsetting heterogeneous treatment effects of opposite signs. Thus, experimental interventions aimed at manipulating beliefs require carefully measured priors (and ideally posteriors as well) to determine exactly how the treatment affects particular individuals’ beliefs, and through beliefs, behavior.
We overcome these obstacles as follows. First, we study participation within an ongoing, high-stakes political movement: Hong Kong's antiauthoritarian movement.5 Because Hong Kong's democrats traditionally protest the rule of the Chinese Communist Party (CCP) each July 1, there exists a known protest about which we can elicit beliefs prospectively in real time. Second, using a three-part online experiment we conducted at the Hong Kong University of Science and Technology (HKUST), we are able to elicit the prior beliefs of more than 1,200 university students regarding the protest turnout of their classmates in the upcoming July 1 march (in an incentivized manner); we are then able to provide an information treatment to a random subset and elicit posterior beliefs (again in an incentivized manner); finally, we are able to elicit the students’ own protest participation.