It found the more people involved in making a decision, the bigger the greater the chance of bad decisions.
The "wisdom of crowds theory was based on observations by English statistician Sir Francis Galton's more than a century ago who stated group decisions are enhanced as more individuals have input. He observed a contest in which villagers attempted to guess the weight of an ox and although not one of the 787 estimates was correct, the average of the guessed weights was a mere one-pound short of the animal's recorded heft.
But collective decision-making has rarely been tested under complex, "realistic" circumstances where information comes from multiple sources The new study, published in the journal Proceedings of the Royal Society B, used simulations to investigate how numbers of individuals effected their ability to make a decision. The group's decision accuracy was determined by how well individuals could use two types of information. One that was known to all members of the group - known as correlated information - and another that was perceived by only some individuals, or uncorrelated information.
Albert Kao, a graduate student of ecology and evolutionary biology who co-authored the study, said with more individuals, that which is known by all members comes to dominate the decision-making process.
The uncorrelated information gets drowned out, even if individuals within the group are still well aware of it.
In smaller groups, on the other hand, the lesser-known cues nonetheless earn as much consideration as the more common information. This is due to the more random nature of small groups, which is known as 'noise' and typically seen as an unwelcome distraction. Mr Kao found that noise is surprisingly advantageous in these smaller arrangements and said: "It's surprising that noise can enhance the collective decision".
The majority cannot decide well.
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