Washington, Sep 2 (IANS): Why do people with above average intelligence act irrationally, especially when they are drunk?

A new study says that alcohol dulls the brain signal warning people about mistakes, reducing their self control.

"When people make mistakes, activity in a part of the brain responsible for monitoring behaviour increases... sending an alarm signal to other parts of the brain indicating that something went wrong," said Bruce Bartholow.

Bartholow, associate professor of psychology at the University of Missouri, Columbia, and his team measured brain activity of 67 participants, aged 21-35 years, as they completed a task designed to trip them into making errors.

About a third of them were given alcohol, while the rest were given no alcohol or a placebo beverage, the Journal of Abnormal Psychology reports.

Besides monitoring brain activity, researchers also measured changes in participants' mood, their accuracy in the computer task, as well as their perceived accuracy, according to a Missouri statement.

The findings showed that the brain's "alarm signal" in response to errors was much less pronounced in those who had consumed alcohol, and the response was the largest for those in the placebo group.

However, those in the alcohol group were no less likely to realize when they had made a mistake than participants in the other groups.

It indicates that alcohol's reduction of the brain's "alarm signal" did not occur simply because those in the alcohol group were unaware of their errors.