When are two heads better than one?

The Challenger disaster, the Bay of Pigs fiasco, the botched invasion of Iraq ... all these historical calamities have been blamed on dud group decision making. Bang heads together, it seems, and you dull people's minds.

And yet there's the almost-magic "Wisdom of Crowds" effect - average people's verdicts together and you'll arrive at a more accurate answer than any one person would have achieved on their own.

How to resolve this paradox? A series of intriguing new studies discussed on our Research Digest provides part of the answer, highlighting the roles played by people's confidence and the type of problem they're tackling.