Perhaps unsurprisingly, research has found that the consumption of alcohol increases aggression. In fact, excessive alcohol consumption is involved in a majority of violent crimes, including rape and murder (Abbey, Ross, McDuffie, & McAuslan, 1996). The evidence is very clear, both from correlational research designs and from experiments in which participants are randomly assigned either to ingest or not ingest alcohol, that alcohol increases the likelihood that people will respond aggressively to provocations (Bushman, 1997; Graham, Osgood, Wells, & Stockwell, 2006; Ito, Miller, & Pollock, 1996). Even people who are not normally aggressive may react with aggression when they are intoxicated (Bushman & Cooper, 1990).
Alcohol increases aggression for a couple of reasons. First, alcohol disrupts executive functions, which are the cognitive abilities that help us plan, organize, reason, achieve goals, control emotions, and inhibit behavioral tendencies (Séguin & Zelazo, 2005). Executive functioning occurs in the prefrontal cortex, which is the area that allows us to control aggression. Alcohol therefore reduces the ability of the person who has consumed it to inhibit his or her aggression (Steele & Southwick, 1985). Acute alcohol consumption is more likely to facilitate aggression in people with low, rather than high, executive functioning abilities.
Second, when people are intoxicated, they become more self-focused and less aware of the social situation, a state that is known as alcohol myopia. As a result, they are less likely to notice the social constraints that normally prevent them from engaging aggressively and are less likely to use those social constraints to guide them. We might normally notice the presence of a police officer or other people around us, which would remind us that being aggressive is not appropriate, but when we are drunk we are less likely to be so aware. The narrowing of attention that occurs when we are intoxicated also prevents us from being aware of the negative outcomes of our aggression. When we are sober, we realize that being aggressive may produce retaliation as well as cause a host of other problems, but we are less likely to be aware of these potential consequences when we have been drinking (Bushman & Cooper, 1990).
Alcohol also influences aggression through expectations. If we expect that alcohol will make us more aggressive, then we tend to become more aggressive when we drink. The sight of a bottle of alcohol or an alcohol advertisement increases aggressive thoughts and hostile attributions about others (Bartholow & Heinz, 2006), and the belief that we have consumed alcohol increases aggression (Bègue et al., 2009).