Alcohol and aggressive behavior are clearly linked. A study of the effects of anger on alcohol-related aggression has found that intoxicated individuals will display more facial expressions of anger than will sober individuals. Individuals who express anger outwardly are at particularly high risk of alcohol-related aggression when strongly provoked.

The relationship between alcohol and aggressive behavior is well known. The modulating effects of personality and anger on alcohol-related aggression, however, are less clear. A study of drinkers’ facial expressions of anger, published in an issue of Alcoholism: Clinical & Experimental Research, finds that drinking alcohol may place those individuals with a tendency toward anger at greater risk of becoming aggressive.

“When most people think of anger, they probably think of the emotional state,” said Amos Zeichner, professor and director of the Psychology Clinic at the University of Georgia, and corresponding author for the study. “This is when we get mad in response to some form of provocation. The personality trait of anger refers to a person’s general tendency to experience chronic anger over time. Such an individual tends to search in his or her environment for stimuli that may activate feelings of anger, which may explain why he or she is more often angry compared with a person who does not have this personality trait.”

The association between alcohol and aggression is huge, according to Robert O. Pihl, professor of psychology and psychiatry at McGill University. “Alcohol is involved in half of all murders, rapes and assaults,” he said. “But the dynamics of this association are complicated, which is why any research that focuses on elucidating this relationship is important for society in general.”

Researchers recruited 136 male social drinkers between the ages of 18 and 30 years from undergraduate psychology courses and via local media advertisements. During a 20-minute session (followed by a 10-minute waiting period): the alcohol group (63) consumed two beverages consisting of ethanol and orange juice, bringing them to a blood alcohol concentration of 0.08%; the control group (73) consumed two beverages consisting of just orange juice. Participants were told they were then going to compete against another individual on a “reaction time” task, during which they might receive electric shocks from their opponent. While engaged in this fictitious task, which included both high and low shock levels or “provocation,” the participants’ experience of anger was unobtrusively assessed using the Facial Action Coding System, which classifies all observable facial activity into 44 unique “action units.” Intoxicated participants displayed more facial expressions of anger than sober participants.

“Practically, facial expression is probably one of the best ways of knowing if someone is angry,” said Pihl. “Even infants can detect that emotionality. And frankly, how else are you going to measure anger? Asking somebody doesn’t work because people are not very good at discerning their emotions, and sometimes they just lie. That’s why Paul Ekman’s Facial Action Coding System has been proven so valuable in discerning lying, anger, and other kinds of things.”

Intoxicated participants also demonstrated a positive relationship between facial expressions of anger and the tendency to express anger outwardly after high (but not low) provocation.

“Alcohol intoxication brings out people’s natural tendencies in the expression of anger,” said Dominic Parrott, the graduate student who conducted the study. “Our findings strengthen the notion that alcohol increases the likelihood that certain drinkers, particularly those with the tendency to be angry and to express their anger outwardly, become aggressive when provoked.”

The term, “Anger-Out,” reflects an individual’s tendency to express his or her anger outwardly, such as verbal aggression (yelling or screaming) and/or physical aggression towards inanimate objects (kicking the wall) or other individuals (punching or shoving). “Anger-In” is the tendency toward “fuming,” “churning inwardly,” or “boiling up” with anger. Individuals with high levels of this trait may not express their anger outwardly, yet they still do not effectively cope with their anger. “Anger-Control” reflects a person’s tendency to control or cope with his or her anger in a way that reduces the likelihood of anger-related outbursts or “seething.”

“If individuals tend to express their anger outwardly,” said Zeichner, “alcohol will ‘turn up the volume,’ so that such a person will express anger more frequently and more intensely. A heightened response will most likely occur when the provocation against the drinker is a strong one, and will less likely occur when the individual is experiencing a low provocation and is sober.”

In summary, said Zeichner and Parrott, “our findings suggest that we need to understand that emotions and their regulation play an important role in the relationship between drinking and behaving aggressively. If this role is proven true, then it would be helpful to teach certain drinkers to moderate their use of alcohol, help them to effectively cope with their anger and, finally, learn how to respond to provocation in a de-escalating manner.”