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Herd mentality: Are we programmed to make bad decisions?

Dec. 16, 2014
Courtesy of the University of Exeter
and World Science staff

A de­sire to be part of the “in crowd” is a result of our evo­lu­tion—but can dam­age our abil­ity to make good de­ci­sions, a new study pro­poses.

The re­search con­cludes that groups are less re­spon­sive to changes in their nat­u­ral en­vi­ron­ment be­cause in­di­vid­u­als have evolved to be overly in­flu­enced by their neigh­bors. The in­vest­i­ga­tors used math­e­mat­i­cal mod­els to ex­am­ine how the use of so­cial in­forma­t­ion has evolved with­in an­i­mal groups.

“Copy­ing what oth­er in­di­vid­u­als do can be use­ful in many situa­t­ions, such as what kind of phone to buy, or for an­i­mals, which way to move or wheth­er a situa­t­ion is dan­ger­ous,” said Col­in Tor­ney of the Uni­vers­ity of Ex­e­ter in the U.K., lead au­thor of a pa­per on the find­ings.

But “the chal­lenge is in eval­u­at­ing per­son­al be­liefs when they con­tra­dict what oth­ers are do­ing. We showed that ev­o­lu­tion will lead in­di­vid­u­als to over use so­cial in­forma­t­ion, and copy oth­ers too much… the re­sult is that groups evolve to be un­re­spon­sive to changes in their en­vi­ron­ment and spend too much time cop­ying one anoth­er, and not mak­ing their own de­ci­sions. “

The study is pub­lished in the Dec. 17 is­sue of the research jour­nal In­ter­face.

By us­ing a sim­ple mod­el of decision-mak­ing in a chang­ing en­vi­ron­ment, the team found that in­di­vid­u­als overly rely on so­cial in­forma­t­ion and evolve to be too readily in­flu­enced by their neigh­bors. The re­search­ers sug­gest this is due to a “clas­sic ev­o­lu­tion­ary con­flict be­tween in­di­vid­ual and col­lec­tive in­ter­est.”

“Our re­sults sug­gest we should­n’t ex­pect so­cial groups in na­ture to re­spond ef­fec­tively to chang­ing en­vi­ron­ments. In­di­vid­u­als that spend too much time cop­ying their neigh­bors [are] likely to be the nor­m,” Tor­ney said.


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A desire to be part of the “in crowd” is part of our evolution—but can damage our ability to make good decisions, a new study has found. The research concludes that groups are less responsive to changes in their natural environment because individuals have evolved to be overly influenced by their neighbors. The team used mathematical models to examine how the use of social information has evolved within animal groups. “Copying what other individuals do can be useful in many situations, such as what kind of phone to buy, or for animals, which way to move or whether a situation is dangerous,” said Colin Torney of the University of Exeter in the U.K., lead author of a paper on the findings. But “the challenge is in evaluating personal beliefs when they contradict what others are doing. We showed that evolution will lead individuals to over use social information, and copy others too much… the result is that groups evolve to be unresponsive to changes in their environment and spend too much time copying one another, and not making their own decisions. “ The study is published in the Dec. 17 issue of the journal Interface. By using a simple model of decision-making in a changing environment, the team found that individuals overly rely on social information and evolve to be too readily influenced by their neighbors. The researchers suggest this is due to a “classic evolutionary conflict between individual and collective interest.” “Our results suggest we shouldn’t expect social groups in nature to respond effectively to changing environments. Individuals that spend too much time copying their neighbors is likely to be the norm,” Torney said.