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Mechanical Turk, Dynamic Networks, and Cooperation

In a fun paper recently published in PNAS, Dynamic social networks promote cooperation in experiments with humans, Dave Rand, Nicholas Christakis, and I explored how a dynamic social network affects cooperation. Scientists have been using the public goods game for a long time to understand people’s tendency to cooperate with others. Recently, research has explored whether it’s important to array people in a network that looks like a real-world social network in order to foster cooperation. However, this doesn’t seem to increase cooperation among people.

We examined whether the secret ingredient in creating cooperation was a dynamic social network: we give people the ability to change the structure of your own social network. Someone screwing you over? No need to simply defect, rather than cooperate. You can now just stop interacting with them. Theory dictates that if we would allow a lot of rewiring, actions have consequences, and you get a lot of cooperation. And that is exactly what we found. To quote our abstract:

Human populations are both highly cooperative and highly organized. Human interactions are not random but rather are structured in social networks. Importantly, ties in these networks often are dynamic, changing in response to the behavior of one’s social partners. This dynamic structure permits an important form of conditional action that has been explored theoretically but has received little empirical attention: People can respond to the cooperation and defection of those around them by making or breaking network links. Here, we present experimental evidence of the power of using strategic link formation and dissolution, and the network modification it entails, to stabilize cooperation in sizable groups.

And we did this all on Amazon Mechanical Turk, a great place to run social science experiments. As Dave (my co-first author) notes:

“Lab experiments are incredibly valuable, because they let you very tightly control the experimental conditions, which you need to demonstrate causality,” Rand said. “But the thing about lab experiments is they tend to be very time-consuming and expensive, because it’s difficult to get people to come into the lab. The Internet offers an amazing opportunity for streamlining the process. But the problem has been: Where do you get the people, and how do you set these systems up?”

Developed several years ago, Mechanical Turk is an online labor market where employers can hire workers to perform what they call “human intelligence tasks” — simple, repetitive ones that are easy for humans — such as describing the content of a picture, transcribing audio or translating text from one language to another — but are frustratingly difficult to program computers to perform.

“What we’re doing is crowd-sourcing experimental social science,” Rand said. “We are now an ‘employer’ on Mechanical Turk, but instead of asking people to label images, we’re hiring them to take part in our experiments.

“From a philosophical perspective, I think this is an amazingly important technology for the social sciences, because it’s democratizing,” Rand continued. “You no longer need to be at a university that has a big lab, with a huge research budget and someone maintaining a subject pool. Now anyone who has an idea can spend a day building a survey online, post it on Mechanical Turk, and see what happens.”

The paper has a number of other interesting results, which can be seen here, or read about at the Harvard Gazette.

Personalized Subways

In the September issue of Scientific American, the editors asked a number of people about an innovation that would make cities more livable. My answer? Personalized subways:

Transportation innovation is one of the keys to creating a more livable city. And one innovation that has the potential to greatly impact life through transportation is personal rapid transit. Personal rapid transit is essentially a personalized subway system for a city. These systems use pods that can hold a handful of people, carrying them directly from point to point, with no stops and no waiting at stations. Creating an easier way to navigate a city promotes interactions among its inhabitants and, in turn, a more livable, and potentially more productive, city.

Here’s more about personal rapid transit. And the rest of the answers are here.

Traces of Humanity

I have an article in this week’s Ideas section of the Boston Globe titled Traces of Humanity: What aliens could learn from the stuff we’ve left in space. In commemoration of the forty year anniversary of the placement of the Fallen Astronaut monument on the moon, I explore how what we place in space, consciously or otherwise, paints a picture of humanity:

If you were to visit the moon today, in the neighborhood of the Apennine mountain range, you would find a small figurine, about the same size and shape as a Lego minifigure, lying facedown in the lunar dust. Unauthorized by NASA, this “Fallen Astronaut” sculpture was placed there exactly 40 years ago this past week by astronauts David Scott and James Irwin of Apollo 15, and sits alongside a tiny plaque listing the names of 14 astronauts and cosmonauts who had died during their time in their respective space programs.

This haunting miniature memorial is only one of the many artifacts and messages that human beings have deliberately sent into space, or left there, as a symbol of our presence. On Earth, most of human history has involved unconsciously leaving traces of our existence, from garbage to aqueduct ruins. But when we go into space, we can begin to make choices about what we leave to posterity.

The rest is here.

The Life-Spans of Empires

I recently published my first history article. Titled The Life-Spans of Empires, it’s published in the delightfully-named journal Historical Methods: A Journal of Quantitative and Interdisciplinary History. Using a fun dataset I unearthed from some articles in the Nineteen Seventies, I explore the lifespans of empires, and their similarities to other complex systems:

The collapse of empires is exceedingly difficult to understand. The author examined the distribution of imperial lifetimes using a data set that spans more than three millennia and found that it conforms to a memoryless exponential distribution in which the rate of collapse of an empire is independent of its age. Comparing this distribution to similar lifetime distributions of other complex systems—specifically, biological species and corporate firms—the author explores the reasons behind their lifetime distributions and how this approach can yield insights into empires.

This mathematical approach is part of a growing field of cliodynamics, a term coined by scientist Peter Turchin to describe the use of quantitative rigor in understanding history (there’s a new journal too of the same name). I look forward to more analyses that explore the long sweep of time using math.

Samuel Arbesman (2011). The Life-Spans of Empires Historical Methods, 44 (3), 127-129 : 10.1080/01615440.2011.577733

In Praise of Mediocre Research

The incredible Longshot Magazine–a project that creates an entire magazine in 48 hours–just completed its most recent issue, with the unifying theme of debt. I wrote a piece that was selected, In Praise of Mediocre Research, which is all about how each scientist is indebted to those who have come before them. And how, unsurprisingly, we can study how that process works:

In science, we are in hock to our forebears. If not for the discovery of DNA, Watson and Crick would not have been able to unravel its structure. If not for Newton’s theory of gravitation, we would not have Einstein’s theory of general relativity. Science is cumulative. But the process of deciding which research is most worthy of accumulating offspring is controversial… and not exactly elegant.

The value given to a scientific endeavor relies on cumulation and indebtedness (combined with making sure that researchers receive credit where it is due). Citations– footnotes at the end of a paper that list the author’s inspirations–form the foundation of novel research. Most papers, while they may have numerous references within them, are rarely or never cited by other papers. Their contribution to science is viewed as minimal. It is only the standouts–the lucky, and the rare–that accumulate citations.

The rest is here.

Sidewalk Astronomy

Going back to the late Nineteenth and early Twentieth Centuries, there has been a tradition of sidewalk astronomy. Sidewalk astronomy is really just what it sounds like: using a telescope on the sidewalk or street corner. Whether for free or for a small fee, these astronomers enticed the public to engage with outer space in an informal and exciting way.

More recently, John Dobson, an amateur astronomer, has brought sidewalk astronomy to the people of San Francisco. Beginning in the Nineteen Sixties, he has been engaging the public, even founding the organization of San Francisco Sidewalk Astronomers. Dobson also created a simple way for amateurs to build large telescopes, which are now known as Dobsonian telescopes:

The night is full of wondrous things—giant galaxies that look like pinwheels, clusters where stars swarm like bees, gauzy nebulae adrift in the Milky Way—but most of these lie beyond the capacity of the human eye. A large telescope—the larger the better to gather light—makes these objects visible. Says legendary comet-hunter David Levy, borrowing a thought from Bob Summerfield, co-director of Astronomy To Go, a traveling star lab: “Newton made telescopes for astronomers to observe the universe; John Dobson makes telescopes for the rest of us.”

Nearly a million people have looked through Dobson’s telescopes, which he constructs from castoff pieces of plywood and scraps of two-by-fours, cardboard centers of hose reels, chunks of cereal boxes and portholes from old ships. He puts his scopes on portable mounts that swivel sideways and up and down. “The Dobsonian Revolution was with just letting people look through the big telescopes, which was an extraordinary thing to do,” says Levy. “I think every advanced amateur astronomer in the world has at least one Dobson telescope.”

More here.

Science, Technology, and Google News

Recently, Google News separated its Science and Technology sections into two distinct parts. This seems to have been desired for some time and is a welcome change.

For many people, technology and engineering are part of the same intellectual package that science is a part of. But that’s not really true. While it’s sometimes difficult to distinguish the two–the fruits of each can lead to breakthroughs in the other–they are distinct. Henry Petroski, a professor at Duke, wrote a thought-provoking article in IEEE Spectrum in December 2010 titled Engineering is Not Science, about this distinction:

Science is about understanding the origins, nature, and behavior of the universe and all it contains; engineering is about solving problems by rearranging the stuff of the world to make new things. Conflating these separate objectives leads to uninformed opinions, which in turn can delay or misdirect management, effort, and resources.

Take this year’s oil spill in the Gulf of Mexico. No one, to the best of my knowledge, blamed it on science. Poor engineering decisions allowed gas to escape from a well in deep water, which in turn caused a fatal explosion. Subsequently, the engineered blowout preventer failed, and for months oil escaped into the environment. Poor engineering got us into the mess; surely only good engineering could get us out of it. Yet repeatedly, government and other research scientists were allowed to veto the engineering tactics needed to stanch the flow. In the end, of course, it was engineering that finally capped the well.

Throughout history, a full scientific understanding has been neither necessary nor sufficient for great technological advances: The era of the steam engine, notably, was well into its second century before a fully formed science of thermodynamics had been developed. Indeed, sometimes science has impeded progress. Had Marconi believed his physicist contemporaries, he would have “known” that wireless telegraphy signals could not be sent across the ocean, around Earth’s curvature.

Engineers welcome any and all available scientific knowledge, but they needn’t wait for scientists to give them the go-ahead to invent, design, or develop the machinery to advance technology or to check it when it runs out of control. Without understanding this, we will continue to underfund the engineering needed to solve our greatest problems.

Thanks to @underSixFoot for the pointer to the change in Google News.

Baseball Teams and Jet Lag

Do baseball teams that have to travel across time zones, and are therefore subject to jet lag, more likely to lose games? This question, resulting in the concept of circadian advantage, was taken up in a letter in Nature back in 1995:

Many factors undoubtedly contribute to winning baseball games, but our data indicate that one critical, previously unrecognized component of the ‘home field’ advantage of east and west coast baseball teams involves previous transcontinental travel by the visiting team within the preceding two days, but only if the direction of travel is eastward…

While the performance decrements described her might seem small in magnitude, their consequences for competitive athletics are substantial.

More here (subscription required).

Announcement: Position at the Kauffman Foundation

This is one of those announcement posts: I’m finishing my postdoc at Harvard this summer and, as of mid-August, I will be beginning a position as a Senior Scholar at the Ewing Marion Kauffman Foundation. The Kauffman Foundation is devoted to understanding entrepreneurship, broadly construed, and is one of those places positively brimming with interdisciplinary and ground-breaking ideas. I am incredibly excited about this opportunity, where I will be getting the chance to think about innovation and growth, how cities develop and act as engines of productivity, and lots of other cool ideas. And of course, I will continue to do lots of popular writing.

Anyway, as the Kauffman Foundation is based in Kansas City, I’ll leave you with a Grantland article by Chris Suellentrop about Hard Times in the Paris of the Plains.