[Paleopsych] Eureka: Study shows how consensus is attained in a noisy world

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Study shows how consensus is attained in a noisy world
    Contact: Megan Fellman
    [2]Northwestern University

             Study shows how consensus is attained in a noisy world

    EVANSTON, Ill. -- A month before the fall of the Berlin Wall, 70,000
    people gathered in the streets of Leipzig, East Germany, on Oct. 9,
    1989, to demonstrate against the communist regime and demand
    democratic reforms. Clearly, no central authority planned this event;
    so how did all of these people decide to come together on that
    particular day?

    A new study by researchers at Northwestern University sheds light on
    how individuals might obtain information about the decisions and
    preferences of other individuals with whom they do not have a
    relationship or even contact. The findings are published online this
    week (Aug. 2) by the Proceedings of the National Academy of Sciences

    The Leipzig demonstration is an example of a complex system, the
    result of an evolving process. The common characteristic of complex
    systems, whether they be social or biological in nature, is that they
    display organization without any external organizing principle being

    "How did a consensus come about? Our computer model shows how social
    networks can substitute for central mechanisms in decision making,"
    said Luís A. N. Amaral, associate professor of chemical and biological
    engineering and an author on the PNAS paper. "Surprisingly,
    information can be aggregated more efficiently if local information
    transmission is not perfectly reliable but is subject to error or
    random noise, due to lack of trust, indecision or unreliable
    information technologies."

    For the citizens of Leipzig, the "noise" was the presence of the
    Stasi, the state secret police. "The need of individuals to avoid
    certain forms of communication, due to fear of the Stasi, might
    actually have contributed to the more efficient spread of information
    about a generalized dissatisfaction with the regime and the
    willingness to take a stand against it," said Amaral.

    The Northwestern study also clarifies how social norms might quickly
    be adopted and remain ingrained within society and how unicellular
    organisms might organize into multi-cellular structures.

    The researchers show that a simple majority rule approach, in which
    each unit -- a person or a cell -- adopts the state of the majority of
    its neighbors within an intricate communication network, can
    efficiently lead to global organization. The model is adaptable and
    robust -- a real-world system capable of responding to external

    "In real life we use simple rules to decide what to do," said Amaral.
    "People tend to adjust their opinions based on what the majority is
    telling them."

    In addition to Amaral, other authors on the PNAS paper are André A.
    Moreira, Abhishek Mathur and Daniel Diermeier, from Northwestern
    University. Diermeier is co-director of Northwestern's Institute for
    Complex Systems.


    2. http://www.northwestern.edu/

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