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With Lure of Cash, M.I.T. Group Builds a Balloon-Finding Team to Take
Pentagon Prize
Published: December 6, 2009

A group of researchers at the Massachusetts Institute of Technology edged
out about 4,300 other teams on Saturday in a Pentagon-sponsored contest to
correctly identify the location of 10 red balloons distributed around the
United States.

The contest, which featured a $40,000 prize, was organized by the Defense
Advanced Research Projects Agency, in an effort to develop new ways to
understand how information is disseminated through social networks.

The winning group, a small team at the M.I.T. Media Laboratory Human
Dynamics Group led by a physicist, Riley Crane, took just eight hours and 56
minutes to complete the challenge.

The balloons, which were 8 feet in diameter, were arrayed around the
country. Some were in highly trafficked locations like Union Square in San
Francisco; others were in more obscure places, like Katy Park, a baseball
field in the Houston suburbs.

The winning researchers, who specialize in studying human interactions that
emerge from computer networks, set up a Web site asking people to join their
team. They relied on visitors to the Web site to invite their friends. They
also sent e-mail messages inviting people to participate and sent a small
number of advertisements to mobile phones.

They said that they would dole out the prize money both to chains of
individuals who referred people who had correct information on the balloons'
locations and to charities. They described their method as a "recursive
incentive structure."

The approach "rewards people who make real contributions," said Dr. Crane,
whose research has recently focused on how information spreads in computer
networks, like YouTube.

"This was a once-in-a-lifetime opportunity to perform an experiment at a
massive scale," he said.

In the simplest case, a single person who contributed the correct answer
would be given $2,000 and the research group would give another $2,000 to
charity. In cases where multiple people contributed, participants will get
some fraction of $4,000.

The researchers said they had received contributions from 4,665

"They got a huge amount of participation from shockingly little money," said
Peter Lee, a DARPA project manager who was one of the organizers of the
Network Challenge.

DARPA had begun holding similar events focused on autonomous vehicles in
2004 to create incentives to quickly advance the state-of-the-art. In the
Network Challenge roughly 500 teams had made a serious effort and come close
to identifying all of the balloons in a contest that Dr. Lee referred to as
a "nail-biter."

He said while they were planning the event the DARPA scientists had wondered
about the relative effectiveness of different motives ranging from profit to
working for the common good.

"In the final results all of the motives seemed to be effective," he said.

The researchers said their technique could be used for many things,
including finding criminals and missing children and halting impending
terrorist attacks. 

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