New research has found that men and women have different patterns of brain activity when it comes to cooperating with others.
The new study from researchers at Stanford University School of Medicine could offer some clues into how cooperative behavior may have evolved differently between males and females.
Researchers add it could eventually help them develop new ways to boost cooperative behavior.
“It’s not that either males or females are better at cooperating or can’t cooperate with each other,” said the study’s senior author, Allan Reiss, M.D., a professor of psychiatry and behavioral sciences and of radiology. “Rather, there’s just a difference in how they’re cooperating.”
While cooperation is vital to human society, not everyone cooperates equally. One factor that shapes a person’s approach to cooperation is gender, according to previous research.
Past studies have found that women cooperate more when they’re being watched by other women; that men tend to cooperate better in large groups; and that while a pair of men might cooperate better than a pair of women, in a mixed-sex pair, the woman tends to be more cooperative.
Theories have circulated about why this is, but the brain science behind them has been scarce, according to the Stanford scientists.
“A vast majority of what we know comes from very sterile, single-person studies done in an MRI machine,” said Joseph Baker, Ph.D., a postdoctoral scholar at Stanford and a lead author of the study.
To figure out how cooperation is reflected in the brains of men and women who are actively cooperating — rather than just thinking about cooperating while lying in a machine — the Stanford researchers used a technique called hyperscanning. Hyperscanning involves simultaneously recording the activity in two people’s brains while they interact.
Instead of using an MRI that requires participants to lie perfectly still and flat, the scientists used near-infrared spectroscopy, or NIRS, in which probes are attached to a person’s head to record brain function, allowing them to sit upright and interact more naturally, the researchers explained.
The 222 participants in the study were each assigned a partner. Pairs consisted of two males, two females, or a male and a female. While wearing the NIRS probes, each person sat in front a computer, across the table from their partner. Partners could see each other, but were instructed not to talk. Instead, they were asked to press a button when a circle on the computer screen changed color.
The goal was to press the button simultaneously with their partner. After each try, the pair were told who had pressed the button sooner and how much sooner. They had 40 tries to get their timing as close as possible.
“We developed this test because it was simple, and you could easily record responses,” said Reiss. “You have to start somewhere.”
He added it wasn’t modeled after any particular real-world cooperative task.
The researchers found that, on average, male-male pairs performed better than female-female pairs at timing their button pushes more closely.
However, the brain activity in both same-sex pairs was highly synchronized during the activity, meaning they had high levels of “interbrain coherence.”
“Within same-sex pairs, increased coherence was correlated with better performance on the cooperation task,” Baker said. “However, the location of coherence differed between male-male and female-female pairs.”
Surprisingly, though, male-female pairs did as well as male-male pairs at the cooperation task, even though they didn’t show coherence, the researchers noted.
Since the brains of males and females showed different patterns of activity during the exercise, more research might shed light on how sex-related differences in the brain inform cooperation strategy, at least when it comes to this particular type of cooperation, the researchers said.
“This study is pretty exploratory,” Baker said. “This certainly isn’t probing cooperation in all its manifestations.”
There could be other cooperative tasks, for instance, in which female-female pairs best males, he noted.
And the researchers point out they didn’t measure activity in all parts of the brain.
“There are a lot of parts of the brain we didn’t assess,” Reiss said, pointing out that interbrain coherence may have been present in other regions of the brain that weren’t examined during the task.
As they continue to study what in the brain underlies cooperation, the scientists’ results could help explain how cooperation evolved in humans, as well as help determine methods that use biofeedback to teach cooperation skills.
“There are people with disorders like autism who have problems with social cognition,” said Baker. “We’re absolutely hoping to learn enough information so that we might be able to design more effective therapies for them.”
The study was published in Scientific Reports.