Introduction: Indonesia holds an extensive record of student protests such as the 1966 Tritura, 1974 Malari, 1998 Reformation, 2012 oil price, and as recent as 2025, the 17+8 demonstrations. These involved physical confrontation with the police, property defacing, and obscene acts of mockery towards unaffiliated people which show destructive behaviours inside a demonstration crowd. Those destructive behaviours are not present when the individuals are not in the crowd. There is a process of identity lost or switch as they become part of the demonstration crowd. To understand the process, we utilized both SIDE model (Reicher et al., 1995) and traditional theories (Festinger et al., 1952; Zimbardo, 1969; Le Bon, 1985). This usage of two theories is due to the present criticisms and countercriticisms on how deindividuation works.


Purpose: This paper aims to understand the factors that lead to deindividuation and the processes of which is involved using both theories.


Method: The data collected were from 150 active college students involved in more than 2 demonstrations. They completed the Deindividuation Scale-Modified by Mikal et al. based on the SIDE model. In addition, interview was conducted based on the traditional theory of deindividuation towards 10 of those 150 students.


Results: College demonstrators exhibited strong group identity and norm-driven behaviour according to questionnaire results. Interviews indicated emotional intensity and decreased self-awareness, which are compatible with classical deindividuation. Findings provide a sophisticated understanding of collective dynamics by highlighting the ways in which social identity influences crowd behaviour, even when anonymity is maintained.


Conclusion: Crowd behaviour reflects both norm adherence and emotional intensity. Combining Social Identity and classical deindividuation offers a balanced understanding of how anonymity and social context influence demonstrator behaviour.