Study co-authors Peter Giancola, a professor at the University of Kentucky, and Brad Bushman, a professor at Ohio State University, and colleagues said people who focus on the here and now, without thinking about the impact on the future, are more aggressive than others when they are sober, but the effect is magnified greatly when they're drunk.
"If you carefully consider the consequences of your actions, it is unlikely getting drunk is going to make you any more aggressive than you usually are," Bushman said in a statement.
Half the participants were put in the alcohol group, where they received alcohol mixed with orange juice at a 1:5 ratio. The other half were given orange juice with a tiny bit of alcohol, but the rims were sprayed with alcohol so that they thought they drank a full alcoholic beverage.
Participants in the alcohol group had a mean blood alcohol level of 0.095 just before aggression was measured.
Aggression was measured via the use of harmless but somewhat painful electric shocks. Each participant was told he or she was competing with an opponent of the same gender in a computer-based speed reaction test -- with the winner delivering and determining the level of the electrical shock to the loser.
"The participants were led to believe they were dealing with a real jerk who got more and more nasty as the experiment continued," Bushman said. "The less people thought about the future, the more likely they were to retaliate, but especially when they were drunk. People who were present-focused and drunk shocked their opponents longer and harder than anyone else in the study."
The study was published online in the Journal of Experimental Social Psychology.