Protests about mandatory vaccination for the construction sector in Melbourne this week got violent pretty quickly. The crowd wasn’t as large as other protests have been, so what made these turn from protest to riot so quickly? Kim Cullen is a psychologist and says it comes down to perceived injustice – in this case not being allowed to work and having the vaccine mandated – as well as being a rudderless crowd. Kim says the protestors didn’t appear to have a leader, and so there was no leader to communicate with and diffuse the situation through. With mounting testosterone in the crowd and an “us” and “them” mentality towards police, the risk of the protest getting violent increased. If protestors perceive an injustice, they need to nominate a leader if they want to achieve a meaningful outcome, Kim says.