Saturday, May 26 , 2018, 6:57 am | A Few Clouds 53º

 
 
 
 

UCSB Psychologists Study Divided Spoils of Cooperation

Many traits make human beings unique, not the least of which is our ability to cooperate with one another. But exactly how we choose to do that — particularly with non-family members — can be complicated.

For males, that choice relies partially on perceptions of productivity and material benefit, just as it would have in an ancestral hunter-gatherer society. So finds a new study by UC Santa Barbara psychologists, which appears in the journal Evolution and Human Behavior.

“It’s interesting that those mechanisms are designed for the environment of our ancestors, not our current context, yet they affect how people behave today,” said lead author Adar Eisenbruch, a Ph.D. candidate in evolutionary psychology.

The researchers used an experimental economics game to determine the traits to which players are sensitive beyond the structure of the game itself.

In this one-shot bargaining construct, the proposer offers a specific split of a fixed sum of money and the responder either unconditionally accepts the offer or rejects it, in which case both players receive nothing.

“Our initial prediction was that men with stronger and more threatening-looking faces — as indexed by width — might be treated better, but that’s not what tended to happen,” explained senior author James Roney, a professor in UCSB’s Department of Psychological & Brain Sciences.

“It turned out that men with wider faces actually were treated worse in the game while men who were physically stronger were treated better,” Roney said. “Our results showed that the choice of cooperative partners isn’t entirely determined by prosocial traits like generosity and trustworthiness, but also by cues that indicate whether someone would have been a productive partner in a hunter-gatherer society.”

Subjects played the game with a set of faces that were rated by a different group for characteristics such as attractiveness, dangerousness, social status and productivity, the last of which represents perceived hunting ability in an ancestral environment.

When the investigators controlled for how productive a man looked, dangerousness became a negative predictor of how well he was treated.

“That makes a lot of sense,” Eisenbruch said. “If you’re going to have a long-term cooperative relationship, you don’t want a partner who looks like he would use his strength to exploit you. You want someone who looks like he has enough strength to be really productive.”

Adar Eisenbruch and James Roney Click to view larger
Adar Eisenbruch and James Roney (Sonia Fernandez / The UCSB Current photo)

Roney noted an important correlation between the degree to which individuals claimed they would want to be friends with people based on their faces, and how well other men treated them in the game.

“What we’re suggesting is that these psychological mechanisms get engaged by the structure of the gam,e and then people act as though it’s a social interaction, as if this were an opening bid to be friends or have a cooperative relationship,” he explained.

In fact, participants actually decreased their earnings in the game by adhering to this approach.

“It seems like the mental mechanisms that people use when they play this game aren’t designed to maximize how much money they make right now,” Eisenbruch said. “Instead, they seem to be designed to secure the best available long-term cooperative relationship based on what partners are available in the environment. Players are willing to sacrifice immediate game earnings in order to do that.”

The same study was repeated with women who played the game with female partners. The psychologists expected to see no effect of strength in women and, in fact, that was true.

“We also found — as you might expect — a weaker effect of productivity in women than in men,” Eisenbruch said. “In women, it seems prosociality trumps productivity, which suggests that men have evolved to engage in specific types of cooperation, like large-game hunting and coalitional warfare, where getting a partner who’s good at those things really, really matters.”

Women cared more about reciprocity. They made higher offers to women who were rated more attractive, healthier and more prosocial, and they also demanded more from attractive partners. On the other hand, men offered more to attractive people but demanded less of them.

“Women in the proposer role would offer more money to attractive women, but in the responder role demanded more from attractive partners,” Roney explained. “It wasn’t that they were always treated better.”

One possible explanation for this, he suggested, is that for women the initial offer of a cooperative relationship with a more attractive partner was accompanied by demands that said: “I also want you to treat me well. Otherwise, I’m not going to accept this relationship.”

These experiments demonstrate that personal characteristics matter in cooperative partner choice, albeit differently across gender lines.

“We’ve not only reframed how subjects interpret the game, but we’ve also shown that people have evolved mechanisms for choosing long-term cooperative partners,” Eisenbruch said. 

Julie Cohen writes for the UCSB Office of Public Affairs and Communications.

 

Support Noozhawk Today

You are an important ally in our mission to deliver clear, objective, high-quality professional news reporting for Santa Barbara, Goleta and the rest of Santa Barbara County. Join the Hawks Club today to help keep Noozhawk soaring.

We offer four membership levels: $5 a month, $10 a month, $25 a month or $1 a week. Payments can be made through PayPal below, or click here for information on recurring credit-card payments.

Thank you for your vital support.

Become a Supporter

Enter your email
Select your membership level
×

Payment Information

You are purchasing:

Payment Method

Pay by Credit Card:

Mastercard, Visa, American Express, Discover

Pay with Apple Pay or Google Pay:

Noozhawk partners with Stripe to provide secure invoicing and payments processing.

  • Ask
  • Vote
  • Investigate
  • Answer

Noozhawk Asks: What’s Your Question?

Welcome to Noozhawk Asks, a new feature in which you ask the questions, you help decide what Noozhawk investigates, and you work with us to find the answers.

Here’s how it works: You share your questions with us in the nearby box. In some cases, we may work with you to find the answers. In others, we may ask you to vote on your top choices to help us narrow the scope. And we’ll be regularly asking you for your feedback on a specific issue or topic.

We also expect to work together with the reader who asked the winning questions to find the answer together. Noozhawk’s objective is to come at questions from a place of curiosity and openness, and we believe a transparent collaboration is the key to achieve it.

The results of our investigation will be published here in this Noozhawk Asks section. Once or twice a month, we plan to do a review of what was asked and answered.

Thanks for asking!

Click Here to Get Started >

Reader Comments

Noozhawk is no longer accepting reader comments on our articles. Click here for the announcement. Readers are instead invited to submit letters to the editor by emailing them to [email protected]. Please provide your full name and community, as well as contact information for verification purposes only.

Daily Noozhawk

Subscribe to Noozhawk's A.M. Report, our free e-Bulletin sent out every day at 4:15 a.m. with Noozhawk's top stories, hand-picked by the editors.

Sign Up Now >