Meetings really can make people more stupid, research confirms.

People trying to solve problems in a group lost around 15% of their IQ.

The drop seems to come from the subtle social signals that people send and receive in groups.

Women are particularly vulnerable to an IQ drop from being in a group, the researchers found.

The study had people working in a group after they had received feedback about an earlier IQ test.

Professor Read Montague, who led the research, explained:
"We started with individuals who were matched for their IQ.

Yet when we placed them in small groups, ranked their performance on cognitive tasks against their peers, and broadcast those rankings to them, we saw dramatic drops in the ability of some study subjects to solve problems.

The social feedback had a significant effect."
While IQ was used to send social signals in this study, in the real world it could be how people speak and what they say.

Or, it could simply be the social hierarchy in an organisation that is known to everyone, whether consciously or not.

Whatever the method, people get the signal about their social standing and this can affect their IQ.

And feeling lower status lowers your IQ.

Dr Kenneth Kishida, the study's first author, said:
"Our study highlights the unexpected and dramatic consequences even subtle social signals in group settings may have on individual cognitive functioning.

And, through neuroimaging, we were able to document the very strong neural responses that those social cues can elicit."
Professor Montague concluded:
"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."
The study was published in the journal Philosophical Transactions of the Royal Society B (Kishida et al., 2012).