Drinking behaviour is affected by culture, upbringing and the immediate social environment.

Men, extrovert people and those with positive expectations regarding alcohol use drink more than others, says Dutch psychologist Sander Bot.

The amount a young person drinks is largely determined by how much others in the group drink. Friendly young people in particular, people who score high on the personality dimension friendliness, are sensitive to the influence of others on their alcohol use.

Besides genetic disposition, drinking behaviour is affected by culture, upbringing and the immediate social environment. Among young people alcohol use is a form of social behaviour. They drink in groups: in private bars, at parties, in clubhouses or at discos. Social alcohol use is strongly dependent on the behaviour and influence of others. This applies to men in particular. Among young people, alcohol addiction is not yet an issue but excessive alcohol use is directly related to, for example, aggression, vandalism and traffic accidents. Hence, it is important to gain a better understanding of the processes that determine how much alcohol a person consumes in the presence of peers.

The research was carried out under young adults aged 18 to 25 years, most of whom did not live at home. Nevertheless, upbringing and the role of the parents still exert a small effect on the amount drunk. For example, a high level of parental support is generally associated with less antisocial behaviour and is correlated with less alcohol consumption in the presence of peers. The drinking behaviour of the father affects that of the young person: if he drinks regularly then the children readily do the same. If, however, he is more reserved then the same response is observed in the child. It is, however, not clear whether this is the result of genetic predisposition or imitation.

The results of this study showed that 12 to 14 year olds are most influenced by classmates with a higher status and those with whom they want to be friends. These differences in influence were, however, not found in the observations of young adults. Here, a high degree of imitation was also found yet no distinction in influence was seen between either best friends or participants with high status, the so-called leader figures. Although these factors may play a role in the decision to actually go on a night out or indeed to leave the drinking situation, but within the situation they make no difference whatsoever.

Sex ratio in the group is a major determinant for alcohol use: the more men present, the greater the amount drunk by both men and women. Possibly a process might be initiated in male groups which ensures that men drink more than usual because participants challenge each other or because no one wants to be surpassed. The observations revealed that men adjust their alcohol use to that of other group members far more than women do. Men also drank more, whereas women stopped drinking earlier in the presence of men who expect that alcohol use leads to sexual excitement.

Previous research had established that people drink less if they are actively involved in a game such as billiards, darts or a card game. However this study reveals that the lower consumption is made up for as soon as the game is over. This means that the total alcohol consumption is not influenced by what people do when they socialise.

Sander Bot was one of the first to observe the drinking behaviour in groups of young adults and combine this with questionnaire data concerning the individual group members. His research was supervised by the Behavioural Science Institute.