Alcohol induces a sort of "social bravery" among men, disrupting processes that would normally prevent them from responding to another person's smile, says an interesting study.
"This experimental study finds the clearest evidence yet of greater alcohol reinforcement for men than women," said psychological scientist and lead researcher Catharine Fairbairn from University of Pittsburgh in Pennsylvania.
Many men report that the majority of their social support and social bonding time occurs within the context of alcohol consumption.
For the study, researchers randomly assigned 720 healthy social drinkers in the age group of 21-28 to groups of three.
Each group was assigned to receive a particular drink: an alcoholic beverage (vodka cranberry), a non-alcoholic beverage, or a non-alcoholic "placebo" beverage that was described as alcoholic.
The researchers smeared the glass of the fake alcoholic drink with vodka and floated a few drops of vodka on top of the drink to make it more believable.
Based on the video recordings, Fairbairn and colleagues used sophisticated analyses to model smiling behaviour in the groups, following the spread of smiles from one individual in a group to the next.
They found that alcohol significantly increased the contagiousness of smiles but only for all-male groups - it did not have a significant effect on emotional contagion for groups that contained any women.
"Consuming an alcoholic beverage may make men more responsive to the smiles of others in their social group," Fairbairn added.
Previous research has shown that men are about 50 percent more likely to drink excessively than women and much problem drinking among men occurs in social settings.
The study appeared in the journal Clinical Psychological Science.