Cool paper! learned a lot about shared beliefs. But I was asking myself "why is 50k traders using similar trading patterns an example of collective intelligence"? I expected an example of a collective accomplishing a group goal as opposed to optimizing individual ability to accomplish goals.

Noted in first paragraph: "we still lack a coherent formal perspective on what human collective intelligence actually is". But, why not reference the closest definition or propose your own rigorous definition of collective intelligence to ground assumptions in the paper?

For instance, in 2007 Legg and Hutter presented a paper, "A Definition of Machine Intelligence" (http://arxiv.org/pdf/0712.3329v1.pdf) which inventoried existing definitions of machine intelligence and suggested their own definition. Seems like these definitional papers would be the starting point for presenting research on any kind of intelligence. Do you see meaningful work in this direction regarding defining collection intelligence?