The Wisdom of Crowds… of Stickleback Fish

By Eliza Strickland | November 14, 2008 11:11 am

stickleback fishIt’s not just we humans who value consensus: A new study has shown that stickleback fish make better decisions when acting as a group than they do as individuals. Researchers set up a clever experiment in which the fish had to choose which leader to follow in the quest for food, giving them an option between a “good” choice and a “bad” choice. Based on earlier experiments, the study’s researchers had a pretty good idea about … stickleback preferences. Fat, evenly colored fish are regarded as healthy and strong, while scrawny fish mottled with black spots may be considered diseased. Coauthor Ashley Ward … says of these sticklebacks, “Fish like large leaders, well-fed leaders and unparasitized leaders” [Science News].

Researchers made a stickleback replica that looked healthy and fat as well as one that appeared bony and mottled, and put both into the fish tank. When shown the fish replicas, the other sticklebacks in the tank would approach and follow one of the two replicas, which were moved around by remote control. Following a certain fish would be their version of casting a ballot…. When just one fish chose its leader, the fish would make the right choice, picking the healthiest leader about 55 percent of the time. That number went up to 80 percent with the eight-fish electorate [LiveScience].

The school of fish arrived at the “correct” answer through a beneficial feedback mechanism, researchers explain in an article in Current Biology [subscription required]. A few fish might catch sight of a potential leader’s unsightly blotches that most of the fish hadn’t noticed, and would strike out to follow the other leader. This behavior is in line with what study coauthor David Sumpter calls the quorum-response rule. In this model, a few individuals are able to discern a difference between the two candidates and so take the lead in making a choice. The rest of the group hangs back, “waiting until a threshold number of fish have made a particular decision,” Sumpter and his colleagues write [Scientific American].

However, researchers warn that it’s not always the best policy to follow the crowd. In a small number of the team’s experiments, all of the fish in a group chose the “bad” leader. “There’s always a danger of amplifying a bad effect” [Science News], comments biologist Stephen Pratt. For an example, researchers say, just look at the bad decisions made by financial institutions over the past few years, which have led to the current economic crisis. Clearly those bankers followed the wrong stickleback.

Image: Wikimedia Commons

  • Becky

    I have never thought of fish making decisions, incredible study! I believe that when it comes to humans I have to agree with Chris Burns, when he states in his newest book, “Deadly Decisions,” that the mind can actually fools us into making the wrong decision- interesting stuff!

  • Alan

    Very Interesting. Perceptions can evidently be used as important propoganda, even in fish. This may help explain why decision by majority (democracy) occasionally chooses quite badly, as in the freely democratic election of Adolph Hilter in Germany. The fish voted for fakes in either case. Were there indications of any groups of fish who refused to choose by following one of them or by following an unintended, volunteer third candidate fish, indicating rejection of both of the fake fish, or did they always follow one of the fakes?

  • Everett Williams


    The problem is almost always insufficient information and insufficient education with a forcing deadline such as an election. With people needing a wheelbarrow of marks to buy a loaf of bread, people were ready for anything that would allow them to survive, in this case, the Nazis. The reason for the collapse was that we chose to continue to punish a whole nation full of people for the actions of their leaders. Both of those lessons should be remembered as we descend into the abyss of what is surely the modern form of a worldwide depression.

  • Elle

    It’s also not just we humans who respond to porn. Studies show that stickleback fish respond to soft porn flicks involving fish.


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