Great article ...
Sharing Information Corrupts Wisdom of Crowds | Wired Science | Wired.com
Similar to mobs you find on online forums like this....
The first they called “social influence”: Opinions became less diverse. The second effect was “range reduction”: In mathematical terms, correct answers became clustered at the group’s edges. Exacerbating it all was the “confidence effect,” in which students became more certain about their guesses. “The truth becomes less central if social influence is allowed,” wrote Lorenz and Rahut, who think this problem could be intensified in markets and politics — systems that rely on collective assessment.
“Opinion polls and the mass media largely promote information feedback and therefore trigger convergence of how we judge the facts,” they wrote. The wisdom of crowds is valuable, but used improperly it “creates overconfidence in possibly false beliefs.”