Everyone’s heard of—or experienced—the “mean drunk” who gets especially ornery when they’re sauced, but research published in Cognitive, Affective, & Behavioral Neuroscience sheds light on the mechanism responsible for the troublesome transformation.
Magnetic resonance imaging (MRI) scans of men’s brains shows that alcohol seems to affect the prefrontal cortex, which is the part of the brain responsible for the moderation of social behavior—including appropriate levels of aggression.
The scans were taken during an experiment by the University of New South Wales. In the experiment, 50 healthy men from 18 to 30 years old volunteered to drink two drinks of either a lemony vodka tonic or a non-alcoholic placebo before playing an experimental rage-inducing game.
The game was simple, when a colored square appeared on the screen, the volunteers had to press the button faster than their “opponent,” who were actually computer-controlled AI. If the volunteers “lost,” they were treated to an annoying blast of noise of varying intensity on a scale of one to four. If they “won,” they could select the intensity of the blast their “opponent” will suffer—and see the level their opponent had selected.
This last bit of information, the researchers reasoned, would let the volunteers know what magnitude of jerk they were dealing with.
The MRI scans of the drunk players showed decreased activity in their prefrontal cortices.
“Aggression is thought to occur because alcohol focuses attention on instigatory cues (such as the noise blasts) and away from inhibitory cues (norms proscribing aggression),” the researchers wrote in the article.
This suggests that the drunk players focused more on how much of a jerk the other “player” was being, and were less focused on the proper way they should be conducting themselves.
While this experiment was illuminating, it’s just a starting point. As always, more research is needed to hone in on where exactly alcohol-induced aggression comes from.
A previous study of the “mean drunk” phenomenon suggested that a drunk person’s inability to predict the consequences of their actions could be a contributing factor to their boozy belligerence. In that study, losers of the game were treated to an electric shock instead.
