Mind: Sharing Information Corrupts Wisdom of Crowds

Do political propagandists make us better informed or worse?

When people can learn what others think, the wisdom of crowds may veer towards ignorance.

In a new study of crowd wisdom — the statistical phenomenon by which individual biases cancel each other out, distilling hundreds or thousands of individual guesses into uncannily accurate average answers — researchers told test participants about their peers' guesses. As a result, their group insight went awry.

They recruited 144 students from ETH Zurich, sitting them in isolated cubicles and asking them to guess Switzerland's population density, the length of its border with Italy, the number of new immigrants to Zurich and how many crimes were committed in 2006.

After answering, test subjects were given a small monetary reward based on their answer's accuracy, then asked again. This proceeded for four more rounds; and while some students didn't learn what their peers guessed, others were told.

As testing progressed, the average answers of independent test subjects became more accurate, in keeping with the wisdom-of-crowds phenomenon. Socially influenced test subjects, however, actually became less accurate.

For more, see Sharing Information Corrupts Wisdom of Crowds by Brandon Keim, May 16, 2011 at Wired.com.