Meetings don"t just eat up time in the workplace, they actually make groups of people stupider, says new research.

Working in a group makes people perform worse on intelligence tests, as some group members are so anxious about doing well that they "divert" their brain power towards maintaining their social status in the group.

"You may joke about how committee meetings make you feel brain dead, but our findings suggest that they may make you act brain dead as well," said Read Montague the study leader at Virginia Tech.

Groups of volunteers showed measurable drops in IQ when asked to perform intelligence tests socially, with the results broadcast to the group.

Some people performed well in the "social" tests, but others were affected badly - and overall, performance dropped.

Women appear to feel this pressure more than men - only three out of 13 female volunteers performed well in a social environment, with 10 out of 13 finding that their peformance dropped.

The researchers used a magnetic resonance imaging (MRI) scanner to monitor how people"s brains responded - and found that bad peformers tended to show activity in parts of their brain that dealt with emotions and anxiety.

"We started with individuals who were matched for their IQ," said Montague. "Yet when we placed them in small groups, ranked their performance on tasks against their peers, and broadcast the rankings, we saw dramatic drops in the ability of some study subjects to solve problems."

"Our study highlights the unexpected and dramatic consequences even subtle social signals in group settings may have on the individual," said lead author Kenneth Kishida.

"We don"t know how much these effects are present in real-world settings. By placing an emphasis on competition, for example, are we missing a large segment of the talent pool?"