SYDNEY, 5 June 2006 - Caffeine can make us a lot easier to persuade, throwing into doubt those decisions reached around the boardroom with a freshly brewed pot of coffee.

In a paper due to be published in the European Journal of Psychology next month, Queensland University psychologist, Pearl Martin says that taking only a moderate dose of caffeine can make us more likely to be persuaded by a good argument, but also more likely to spot a bad one.

"If the argument is strong, forceful and convincing, then people are more likely to see the strength of the argument and be persuaded by it," she said. But she warned that if the argument was not convincing, the caffeine allowed the people to dismiss it more readily.

The team fed orange juice containing 3.5 mg caffeine per kilogram of body weight (equivalent to about two cups of coffee) to university students in the morning, or gave them plain orange juice. Then they asked them to listen to presentations on euthanasia. The caffeinated students were much better able to process information.

"Given the numerous situations in which people are exposed to persuasive arguments, these results could have many applied implications," said Martin, citing political speeches, boardroom discussions and jury deliberations.

But don't go lacing drinks around the office just yet. According to the study's co-author, Blake McKimmie a lecturer in psychology at the Queensland University of Technology, people can become over stimulated by the drug, becoming less likely to focus on messages and more likely to focus on peripheral issues.

Martin said that the team was also unable to rule out the possibility that the effect was simply a function of the experiments being performed in the morning. She said she would like to repeat the experiment at different times of day to eliminate that possibility.