Two psychological phenomena that might be useful to understand today: the frustration-aggression complex, and diffusion of responsibility-deindividuation.
The frustration-aggression complex simply says that one will act aggressively when one is frustrated. Frustration, in psychology, is defined as being hindered in pursuit of a goal. So, if your goal is justice and fair treatment under the law, then you might feel frustrated today. The more this concern about justice affects you directly, the greater the level of frustration you are likely to experience. How physically or emotionally close or how well we identify with the person(s) who experienced injustice, the more we will feel the concern for justice in ourselves. The more helpless we feel in being able to ameliorate our frustration, the more intense and irrational our aggressive response.
Diffusion of responsibility is the phenomenon of relinquishing a sense of responsibility when within a group. This includes both not taking action when we believe that others within the group will take or have taken action and our not taking full responsibility for actions when operating within a group in which most or all of the other members are doing the same or similar things. This is aided by the phenomenon of deindividuation, which is the loss of personal self-awareness within a group context—one identifies as a member of the group more than identifying as an autonomous individual.
These two phenomena combine to provide a psychological context for rioting. Rioting isn’t really about trying to accomplish anything, but as much as a collective statement about not being able to accomplish anything. Applying the standard cause-and-effect paradigm to rioting makes as little sense as the rioting itself. It serves its purpose as statement about feeling helpless.
Throw on top of this the notion that store owners symbolize “having,” whereas experiencing injustice—directly or indirectly—symbolizes “not having” and there is almost a mockery to “having” in the presence of feeling “not having.” Within this skewed mindset, looting feels justifiable—it won’t actually bring about any meaningful effect or change in one’s lie, but it is doing something other than simply swallowing one’s intense frustration (and letting the system of oppression win, as it does on a daily basis).
Rioting is, in a way, a natural behavior given the way the brain processes information to determine which behaviors in which to engage. Sure, it tends to make the situation worse, but that is something only those of us that sit outside of this intense feeling of frustration can truly appreciate.