Looking to study cooperation in action, a team of Harvard social scientists opted to forgo the all too familiar practice of hiring hordes of undergraduates and Cambridge residents as test subjects.

Instead, Human Evolutionary Biology lecturer David G. Rand and his team turned to Amazon.com’s “Mechanical Turk,” a website that recruits thousands of people from around the globe to do work that machines cannot. Amazon labels the site, “Artificial Artificial Intelligence.”

Researchers have used the Mechanical Turk to organize volunteers through the internet to perform basic tasks for pay, such as text transcription and caption composition for online search engines.

Now social scientists like Rand and his team have begun to use the site to hire volunteers for surveys and tests. Compared to a traditional lab, the Mechanical Turk can perform the same studies for a tenth of the time and cost, according to Rand.

“It’s really changing the face of social science studies,” he said.

The subject pool recruited through the Mechanical Turk is “not a true cross-section, but more representative than Harvard undergrads,” said Samuel Arbesman, co-author of the study and a senior scholar at the Kauffman Foundation. “We create a simple model under the assumption that this simple model incorporates a certain amount of truth for the world at large.”

In the study, the research team assigned 800 volunteers an equal number of points to trade. Players could donate their points to their small group or keep the points for themselves.

After each trial, researchers told players about the choices of other group members.

In a paper published Nov. 14 in Proceedings of the National Academy of Sciences, the team, which also included Professor Nicholas A. Christakis, concluded that dynamic social networks promote cooperation and friendliness.

Generous players tended to remain within networks, while selfish players often became isolated.

The threat of social alienation discourages selfish behavior, while cooperative behavior yields social inclusion, the study found.

After exclusion from a group, volunteers who had originally refused to donate their points were twice as eager to cooperate, the study found.

“We know that cooperation is very important for maintaining any society,” Arbesman said. But this study, he said, took a unique approach by examining how cooperation within groups changes over time.

The experiment is among the first to explore the cooperation of large groups within a dynamic social environment, where participants have the power to choose to maintain or abandon certain relationships, Rand said.

Experimenters said the ability of participants to rework their ties to each other within the study emulated a more natural paradigm.

It’s “advantageous to be cooperative,” Rand said.