Q. How does alcohol change behavior?

A. The first thing is that all of us carry around alcohol expectancies, or beliefs about what alcohol does to us and to other people when we drink. Some of these expectancies can be very powerful. [People believe] alcohol makes you have more fun at a social occasion. Alcohol makes you more manly or more attractive or more sexy. The backdrop of any kind of alcohol-fueled event is that for people who are going there, even before they start drinking, the expectancy is that alcohol is going to loosen them up, make things a little more interesting, make them behave in more disinhibited ways. That's something that's very well-documented by researchers. . . . The beliefs drive the behavior.

How does this change when you're in a group?

Alcohol tends to make you respond to really salient cues in your immediate environment. If people are horsing around and you're fueled with alcohol, you're probably going to join in, even in a situation where if you were sober, you'd say, 'This could go in a bad direction.' It makes you more emotional and it makes you more aggressive. . . . The probabilities [of something violent happening] are a lot higher at a football game than if you have 100,000 people in a mall doing shopping. If there are a lot of young people around, and they have a lot of time on their hands, and something whips them up emotionally -- either a win or a loss -- even if they weren't drinking, psychologists will tell you that being in a crowd makes you lose your identity and behave differently than you would on your own. We see that with crowds not helping individuals who are in distress, or examples of crowds becoming lynch mobs.

How can schools prepare to handle tailgating crowds, where alcohol is surely going to be a major factor?

I'm not sure there are any proven ways. Any institution can monitor extreme and intoxicated behavior, and maybe have authority figures around. That adds salient cues in the environment that can prevent the kind of behavior that the crowd could build to otherwise. If you see a uniform on the corner, it's going to be harder to throw yourself into something that can get out of hand.