Aggression linked to alcohol is a big problem. Its causes can include the physical environment, who people are with and how drunk people are. One factor in people's psychological make-up that makes them more likely to become violent when drunk is what psychologists call their "alcohol-aggression outcome expectancy." Put simply, if people expect to become violent when they get drunk they are more likely to end up being violent. A study of 122 students by researchers at Nottingham University looked into the links between heavy drinking, people's natural propensity to become aggressive and their propensity to become aggressive when drunk - a measure which included their alcohol-aggression outcome expectancy. The study found that higher levels of drinking and higher innate aggression both significantly predicted a tendency to become violent when drunk but that innate aggression was the stronger predictor.
McMurran, Mary - The relationships between alcohol use, trait aggression, and the alcohol-aggression outcome expectancy in male students Journal of Substance Use February 2009, 14(1), 1-9