Fish Election 2008

November 14th, 2008

You thought elections season was over didn’t you? Well…it is for us, but studies have shown that fish seem to “elect” their leaders like we do. They don’t go to a voting center and mark a ballot, but they do tend to vote for the one that looks the best for their leader.

“It turned out that stickleback fish preferred to follow larger over smaller leaders,” said Ashley Ward of Sydney University. “Not only that, but they also preferred fat over thin, healthy over ill, and so on. The part that really caught our eye was that these preferences grew as the group size increased, through some kind of positive social feedback mechanism.”

“Their consensus arises through a simple rule,” said David Sumpter of Uppsala University. “Some fish spot the best choice early on, although others may make a mistake and go the wrong way. The remaining fish assess how many have gone in particular directions. If the number going in one direction outweighs those going the other way, then the undecided fish follow in the direction of the majority.”

This is an interesting study really…a lot of the conclusions are based on something theorized about in the 1700’s. The test for whether a group is reaching its decisions on the basis of consensus originated with the French philosopher Condorcet in the 18th century, Sumpter said. Condorcet justified the jury system by showing that the probability that a majority of independent-minded individuals is correct in a decision between “guilty” and “not guilty” increases with group size.

Now, the researchers find, the same is true in schools of stickleback fish making the decision about which leader to follow. Ward presented groups of three-spined sticklebacks with two fish replicas differing in characteristics, including size, fatness, shade, and spottiness, that reflect something about the health or fitness of the individual. For instance, a plump belly can indicate success in food gathering, while spots may indicate a parasitic infection.

He found that in the majority of trials, as the group size increased, they made more accurate decisions on who should be their leader. This wasn’t the same for all, however. In a substantial minority of trials, all or all but one of the fish followed the less attractive leader which did not follow Condorcet’s philosophical ideal.

“Our results show rather that submission to peers and occasional cascades of incorrect decisions can be explained as a by-product of what is usually accurate consensus decision-making,” the researchers wrote. Indeed, Sumpter said, humans make the same types of errors.

“A good example here is the stock exchange,” he said. “Just now there is a lot of discussion about traders unable to make their own assessment and panic selling because others are selling. In these instances, this behavior seems somewhat irrational. But in lots of other scenarios, such behavior is perfectly rational. Watching others and copying them if enough individuals seem to be doing the same thing is generally a good behavioral strategy.”

I’ve got my money on that fish you hang on the wall that sings songs in las vegas this year. I figure that he still has the crowd appeal we are all looking for .