Giovanna Truong, Staff Illustrator
Yale researchers have implemented an imaging technique to peer into the neural systems of people engaging in conversation and study the neural patterns of individuals who are arguing, which could have implications in the study of interpersonal interaction.
For many years, neuroscientists have studied neural systems and activity in the brain, but this research has been limited to one individual at a time. Joy Hirsch, senior author and professor of psychiatry, comparative medicine and neuroscience at the Yale School of Medicine, and her team used data from one of Hirsch’s previous neuroimaging studies and adapted a technique that allowed them to image the brains of two individuals simultaneously while they are engaged in conversation.
Hirsch and her fellow researchers found that when two people are in agreement, there is increased neural activity in the sensory areas of their brains. However, when they disagree, regions of the brain involved in executive decision-making and planning show heightened levels of activity.
“This was a research project that was based on some new advances in interpersonal interaction and being able to look at the neural circuitry of two people engaged in conversation,” Hirsch said. “It is a very new kind of research where we can look at interactions between individuals rather than just single individuals in the scanner. There is a whole new window of opportunity in neuroscience to study live interpersonal interactions between people.”
To perform this study, Hirsch and her team used data that her lab collected in 2015 and has been studying for at least four years. According to Hirsch, they did not have the appropriate tools to properly approach the complex elements of the experiment at first, but as they developed their analysis tools, they were able to proceed.
The researchers recruited 38 individuals and assessed their opinions through an online survey that asked them whether they agreed or disagreed with a series of statements, including “marijuana should be legalized” and “the death penalty should be banned.” Based on their responses, participants were separated into dyads — pairs of individuals — where each pair had agreed on two statements and disagreed on two others.
After matching the pairs, the researchers used an imaging technology called functional near-infrared spectroscopy to record brain activity while the participants engaged in face-to-face conversation.
“Spectroscopy is a fairly universal technique that we use for many things,” said Adam Noah, associate research scientist in psychiatry at the Yale School of Medicine and chief engineer at the Hirsch lab. “It is basically when you use light and you shine it through something to detect what is in it. This technique is defined by these spatially specific changes in blood oxygen concentration.”
Hirsch and her team found that when participants were engaged in conversation about the two topics that they agreed on, brain activity was at a low, consistent level and tended to be concentrated in the sensory areas of the brain. However, when they were in disagreement, the neural activity in both people’s brains was focused on the frontal lobes — the area in charge of high-order executive functions like strategizing and planning.
Hirsch explained that the sensory areas that were active during agreement are part of the more social side of the brain and are responsible for controlling the frontal eye field, which is linked to more eye contact. Agreement also corresponded with increased neural activity in the motor cortex, signaling a greater use of facial expressions such as smiling or nodding.
These results generally predict that the sensory social areas of the brain are active during agreement and that the executive function areas are more active during disagreement.
Hirsch explained that during normal conversation, which can involve agreement or disagreement, “back-channel” cues are used to signal understanding, amongst other things. These back-channel cues occur within the brain and can be studied through acoustical analysis.
When studying the neural patterns of the dyads, researchers also recorded their speech, and this data showed that when disagreeing, people exhibit distinct qualities of speech. Some of these changes included an increase in conversation speed, pitch and overall energy used — measured by blood turnover in the brain — showing that participants put more force behind their articulation when speaking.
The study began after Maurice Biriotti, a founding trustee of the SHM Foundation and chair of medical humanities and enterprise at University College London, approached Hirsch with questions about the way in which people handle conflicts and whether there were any biological processes guiding these reactions. Biriotti ended up working with Hirsch on the study.
“We ran into an interesting problem, which is that neuroscience largely has looked at brains one brain at the time, because to be able to do a lot of the work in imaging you need to put people into a very large scanner,” Biriotti said. “However, lying in a large scanner is not very conducive to having a conversation.”
On one level, the research findings were not surprising to Biriotti. For example, he said that the activity of the frontal lobe seen during disagreement makes sense, due to the decision-making function of this area.
But on another level, he sees something more profound in the results. To him, based on the research, it seems that when people are in disagreement about subjects they are personally interested in, the parts of people’s brains that allow them to be more rational and open are less functional. He said that while one could say the conclusion is obvious, it was interesting to see that there is a biological explanation for the phenomenon. However, Biriotti said that more research has to be conducted to make further conclusions.
The study was published in the journal Frontiers in Human Neuroscience on Jan. 13.
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