We won, so let's go smash some windows!

Philadelphia

FIRES in the streets. Smashed windows. Flipped cars. Light poles toppled by alcohol-fuelled crowds. Philadelphia awoke on the morning after the triumph of Super Bowl Sunday to a city in disarray and this vexing question: What is it about sports that makes fans riot? Why do fans care so intensely about their teams? What is going on in their brains after a win or loss? What circumstances make a riot more likely?

For years, psychologists and sociologists studied this phenomenon of sports fan violence and have found some interesting answers.

Researchers attribute violent behaviour to a heady mix: Intense fan identification with …