If you lock a bunch of high-IQ people in a room and tell them to get on with a simple task, what will they emerge with? Lower IQs, for one thing. A study done by Virginia Tech and a few other institutions, written up over the winter in a publication of the Royal Society, tried to replicate how people think under social pressure. Subjects with an average IQ of 126 were clustered into problem-solving groups and exposed to judgments about their work. A pecking order formed. The low performers showed high responses in the part of the brain that regulates fear. Most of the men became “high performers”, most of the women “low performers”, but no one blossomed. The scientists concluded that “individuals express diminished cognitive capacity in small groups, an effect that is exacerbated by perceived lower status”. In other words, they get dumber.

This confirms common sense. Maybe you can communicate with a slower person by turning off brainpower you have, but you can’t communicate with a cleverer person by creating brainpower you don’t have. Yet this is the first ill word any scientist has had for the way groups think in a very long time. Group intelligence is in vogue. Over the past decade or two, story after story has spoken glowingly of “bandwagon effects” and the “hive mind”, of “memes” and the “wisdom of crowds”. Are these profound new insights or are they a cognitive-science trend on which the tide is now receding?

They are both. There is certainly something measurable that can be called collective intelligence. A fascinating study of its operation was carried out by scientists at Carnegie-Mellon university, MIT and other universities and published in the magazine Science two years ago. The authors started by describing the concept of “g”, or “general intelligence”. The English psychologist Charles Spearman discovered g in 1904, showing that practically all mental tasks are positively correlated. If you’re good at maths, you’re more likely to be a good poet. And since there is an intellectual component to a lot of things we don’t think of as “brainwork”, if you’re a good poet you’re more likely to be a good soldier or a good athlete, too.