Drinking alcohol could make smiles more contagious, but only between men.
The findings suggest alcohol makes men more receptive to rewarding social behaviors and could help researchers gain insight into risk factors for alcoholism, the Association for Psychological Science reported.
"This experimental alcohol study, which included a social context, finds the clearest evidence yet of greater alcohol reinforcement for men than women," said psychological scientist and lead researcher Catharine Fairbairn of the University of Pittsburgh.
Men are about 50 percent more likely to develop drinking problems than women, and the risk is greater in social settings. Many men admit the majority of their social interactions are centered on alcohol.
To make their findings researchers randomly assigned 720 healthy social drinkers between the ages of 21 and 28 to groups of three. Each group was then assigned a to receive and alcoholic, non-alcoholic, or "placebo" beverage that was described as alcoholic. The participants were seated at a table and asked to drink at about the same rate, but otherwise were not given instructions on how to interact.
By looking at video recordings of the sessions the researchers were able to map out how smiles spread across the groups.
The team found alcohol significantly increased the contagiousness of smiles, but only in the all-male group. The findings suggest alcohol triggers a "bravery effect" in men that overrides a process that would prevent them from responding to a smile.
The findings also showed that a smile was more likely to be "caught" across both genders if the individual on the receiving end was a heavier drinker. Smiles that were more likely to be infectious were associated with an increased positive mood and social bonding, which could imply alcohol-related reinforcement in social settings.
"Historically, neither the scientific community nor the general public has been terribly concerned about drinking that occurs in social settings. According to popular opinion, a 'social drinker' is necessarily a non-problem drinker, despite the fact that the majority of alcohol consumption for both light drinkers and problem drinkers occurs in a social context," Fairbairn said.
"Not only that, the need to 'belong' and create social bonds with others is a fundamental human motive," she concluded. "Therefore, social motives may be highly relevant to the understanding of how alcohol problems develop."
