A new hypothesis linking increased aggression to alcohol was tested using electric shocks.

People have long observed that under the influence of alcohol, both physical and emotional pain dulls. Evidence that alcohol raises pain thresholds can also be found in scientific literature. Furthermore, research has shown that the sensitivity to pain positively correlates with aggression.

A group of American and Canadian psychologists suggested that the link between alcohol and aggression is mediated by an increase in pain threshold.

“If sober individuals do not feel their own pain, they may be less inclined to empathize with others when they are in pain. This could lead to more aggressive behavior,” explained one of the authors, communication and psychology professor at Ohio State University, Brad Bushman (Brad Bushman).

To validate their hypothesis, the researchers conducted two laboratory experiments involving regular drinkers, both men and women, who consume three to four alcoholic beverages at least once a month. Two groups of volunteers, consisting of 543 and 327 individuals, were recruited through newspaper advertisements. Participants were compensated with $75 each.

The methods and procedures in the experiments were identical. Participants were randomly assigned to two groups, one offered alcohol and the other a non-alcoholic version. In the second case, a small amount of alcohol was added to an orange juice drink, and the rim of the glass was sprayed with it to mimic the taste and smell of alcohol.

Next, the researchers determined the participants' pain threshold. They received one-second electric shocks to two fingers. The intensity of the shocks was increased until participants reported feeling pain.

In the next phase, volunteers were invited to participate in an online reaction competition. In reality, it was merely a simulation, as winners were announced randomly. According to the rules, the “winning” participant had the opportunity to deliver an electric shock to the “losing” participant, with the intensity reaching the pain threshold at maximum. The researchers also allowed participants to adjust the duration of the shock.

The experiments revealed that the pain sensitivity of those who had consumed alcohol was higher than that of the “placebo” group. Additionally, the less painful the electric shocks felt to the volunteers, the more intense and prolonged shocks they were willing to deliver to others.

“There are many reasons why intoxicated individuals are more likely to intentionally inflict pain on others. This study demonstrated that one possible factor is pain tolerance,” concluded the researchers. Their findings were published in the Journal of Studies on Alcohol and Drugs.

Previously, researchers in the U.S. tracked a large sample of men and women to examine the connection between their IQ levels in high school and their drinking habits many years later in adulthood. It was found that as the IQ of high school students increased, so did their likelihood, at ages 50-60, of being moderate to heavy drinkers rather than teetotalers.