In his book, The Psychology of Group Aggression, psychologist Arnold Goldstein explains theories behind group aggression. Goldstein defined mobs as “a crowd acting under strong emotional conditions that often lead to violence or illegal acts.” He further explained that a riot is “an instance of mob violence, with the destruction of property or looting, or violence against people.” To Goldstein, “mobs are the product of a process of evolution” and they are formed by people sharing the same “conscious or unconscious needs.”

The participants in a riot go through a process of “de–individuation,” which he defines as “the process of losing one’s sense of individuality or separateness from others and becoming submerged in a group.” De–individuation results in the loss of one’s “individual responsibility” as well as the creation of a sense of anonymity, particularly from potential punishment for actions. De–individuated group members are characterized by un–inhibited behavior that is generally against the norm of accepted behavior. De–individuation can be facilitated by the inclusion of other factors such as sensory overload and the introduction of drugs or alcohol.

Another of Goldstein’s theories of mob violence stipulates that individuals who participate in a mob do so because of a sense of deprivation – “the belief that others are climbing up the economic ladder while oneself is not, or the belief that one’s own earlier economic gains are being lost.” He believed that this “sense of blocked opportunity and unjust exclusion from economic gain has been an especially potent. Goldstein argued that riots need a “trigger” or a “precipitating event” to begin.

Goldstein demonstrated that the precipitating event for a riot may take place well before the violence because members of the pending riot may need to “plan and mobilize.” In this context, the precipitating events serve to “confirm the threatening nature of the target group, mobilize ordinary citizens and justify the violence they are about to perpetrate.” Such events could be: “ethnic processions, demonstrations, and mass meetings.”

Following Goldstein’s theories further, riots follow a “common progression” of triggering mechanisms before a final “flashpoint” ignites the riot. Riots begin well before violence breaks out with broad, non-specific factors, including “media sensationalism,” widespread rumors, a large population of unemployed males, and the expectation that rioting will result in change.

Other events in the progress of the riot, such as “seeing friends and allies under attack, the desecration or flourishing of flags, statues, or other sacred symbols” or the “appearance of an especially tempting target” or “particular enemy figure” [in this particular case, Saeimas ēka] sustain the riot and act as new triggers to perpetuate the violence.

Psychologists have observed that riots develop a life of their own once they begin. The first stage of the riot is an attack on property and the riot then moves to attacks on people. As the riot grows and more people join in, the duration of the riot depends on the resistance met by rioters, their organization and leadership, the “success” of their violence and the “degree to which extant authorities send permissive signals encouraging continuance or vigorously intervene.” [We've received reports testifying to the fact that in certain cases “Policija ļāva vaļu notiekošajam”.] The riot may also spread to other areas, sometimes distant from the precipitating site, because of several factors.