Two heads 'may be better than one'
David Cameron and Nick Clegg may take heart from a new study showing two heads really can be better than one.
But another finding might make the Tory and Lib Dem coalition leaders pause for thought.
Solving problems together only works when both partners are equally competent and freely discuss their disagreements, the research authors said.
British and Danish scientists got their heads together to look at what happens when two people pool information to carry out a judgment task.
Pairs of volunteers in a laboratory were asked to detect a weak smudge on a computer screen. If they disagreed about when the signal occurred, they talked together until a joint decision was reached.
The first results showed that joint decisions were more accurate than those made by the better-performing individual alone. In this case, two heads were definitely better than one. Two further tests confirmed that success depended critically on partners being able to talk the problem over.
But a fourth experiment showed that coalitions can be disastrous when partners are mismatched. In this case, one of the volunteers was made to appear incompetent by being shown a "noisy" image in which the signal was much harder to see.
This was not known to the other partner, who continued to trust the first volunteer's judgment. Joint decisions were then worse than the decision of the better-performing partner. In other words, the pair would have been better off if the opinion of the "incompetent" partner had been ignored.
Professor Chris Frith, from the Wellcome Trust Centre for Neuroimaging at University College London, one of the researchers whose findings appear in the journal Science, said: "When two people working together can discuss their disagreements, two heads can be better than one. But, when one person is working with flawed information - or perhaps is less able at their job - then this can have a very negative effect on the outcome.
"Being able to work together successfully requires that we know how competent we are. Joint decisions don't work when a member of the team is incompetent, but doesn't know it."