Being drunk 'a trick of the mind'

Water and limes can make the head spin

The feeling of being drunk is partly in the mind, say psychologists.

A person's memory is impaired if they believe they are drinking alcohol even when it is really water, a study has found.

They had nothing stronger than plain flat tonic water with limes

Dr Maryanne Garry

Researchers at Victoria University in New Zealand tricked 148 students into believing they were drinking vodka to study the so-called placebo effect.

The undergraduates were given drinks in a room set up like a pub with bartenders, vodka bottles and glasses.

Half were told they were drinking vodka and half tonic water. In reality, they were all given plain water with limes.

Afterwards, the students were shown slides of a crime and were asked to assess a story spiked with misleading information.

Memory insights

The researchers found those who thought they were drinking vodka had poorer memory powers than those who knew they were sober. They were also more suggestible and less reliable as eye witnesses.

"We have made people's memory worse by telling them that they were intoxicated even though they had nothing stronger than plain flat tonic water with limes," said co-researcher Maryanne Garry.

"What our research shows is that memory is not just about filing away information like a computer does.

"It's much more than that: memory is what we use to understand and remember events in a social setting, such as witnessing a crime."

Social factors

According to Dr Jim Golby of the University of Teesside in the north of England, it is well known that memory can be affected by perception.

How you perceive a crime is influenced by the state you are in at the time, he said.

He told BBC News Online: "It's not new that memory is affected by social circumstances - that's well documented."

The research is to be published in Psychological Science, a journal of the American Psychological Society.