Uninformed 'vital for democracy'
Uninformed individuals are vital for achieving a democratic consensus, according to a study in the journal Science.
The researchers say that they dilute the influence of minority factions who would otherwise dominate everyone else.
This is because they tend to side with and embolden the numerical majority.
The findings challenge the commonly held idea that an outspoken minority can manipulate uncommitted voters.
"We show that when the uninformed participate, the group can come to a majority decision even in the face of a powerful minority," said lead author Iain Couzin, from Princeton University.
"They prevent deadlock and fragmentation because the strength of an opinion no longer matters - it comes down to numbers. You can imagine this being a good or bad thing.
"Either way, a certain number of uninformed individuals keep that minority from dictating or complicating the behaviour of the group."
But the effect has its limits. The team found that if the number of uninformed becomes too high, a group ceases to function coherently, with neither the majority nor the minority taking the lead.
"Eventually, noise dominates because there just aren't enough informed individuals to guide the group," said Dr Couzin.
The observations come from studying groups of fish, as well as mathematical models and computer simulations.
The experiments involved golden shiners, a fish prone to associating the colour yellow with a food reward. The researchers trained groups of golden shiners to swim towards a blue target, while smaller groups of fish were trained to follow their natural preference for a yellow target.
When the two groups were placed together, the minority's stronger desire for the yellow target dominated the group's behaviour.
But as fish with no prior training (the uninformed individuals) were introduced, the fish increasingly swam toward the blue target preferred by the majority.
Donald Saari, a professor of mathematics and economics at the University of California-Irvine who studies voting systems, said he saw parallels to the work in markets and politics.
He said the arc from minority domination to pluralism to the potential degeneration into "noise," could be seen in the US electoral system.
A forceful minority can dominate in circumstances that attract the more politically inclined, such as mid-term elections and primaries.
In more popular elections, however, that influence waned as less passionate people participated.
Situations in which a candidate's personality or personal life takes precedent over policy positions in voters' minds could be an equivalent to the breakdown in direction the Science study found when there were too many uninformed individuals, Prof Saari said.