How Face-to-Face Disagreements Hijack Available Brain Space

During interpersonal disagreements, cross-brain neural synchrony disintegrates.

Posted Jan 14, 2021 | Reviewed by Matt Huston

Picture yourself sitting outside on a bright, sunny day having a coffee klatch with a good friend at a local café. As you lose yourself in an effortless conversation, there is a sense of togetherness. It feels as if your brains become synchronized, to the point that you could finish one another's sentences. Words flow as you converse freely while simultaneously soaking up all the sensory cues of a beautiful afternoon. At no time during this congenial dialogue does your mind feel taxed or strained to "prove a point."

Now, picture yourself sitting alone on a bench in front of the same coffee shop enjoying the day and watching big puffy white clouds float by when, out of the blue, a stranger sits down a few feet away and strikes up a conversation from the other side of the bench. This random person wants to discuss a hot-button topic that's at the heart of the "culture wars." Within seconds, you realize that as a "dyadic pairing," you're on opposite ends of the political spectrum; your gut instinct is to avoid having a dialogue.

Gerd Altmann/Pixabay
Source: Gerd Altmann/Pixabay

Regrettably, something this person said made your blood boil. In a rage-filled moment, you find yourself engaging with your "opponent" like a political candidate on a debate stage. Within seconds, you can feel your mind working overtime to think of optimal ways to articulate your point of view and win the argument. Because you're determined to convince this interlocutor that he or she is "wrong," you no longer have the mental bandwidth to notice changes in the weather or anything else that's going on in the surrounding environment; this face-to-face disagreement totally consumes your brain.

Anecdotally, most of us can imagine how our brains function differently during pleasant conversations vs. disagreeable conversations. This week, an international team of researchers from the Yale School of Medicine and University College London published a paper, "Interpersonal Agreement and Disagreement During Face-to-Face Dialogue: An fNIRS Investigation," that gives us a peek inside the brain during these two types of social interaction. This functional near-infrared spectroscopy study (Hirsch et al., 2021) was published on Jan. 13 in the peer-reviewed journal Frontiers in Human Neuroscience.

For this study, the researchers recruited 38 study participants who filled out a questionnaire that asked each person to rate how strongly they agreed or disagreed with statements such as "marijuana should be legalized," "video games are a waste of time," "same-sex marriage is a civil right," and "the death penalty should be banned." After the researchers assessed each individual's a priori opinion on these topics, they divided them into pairs they knew would either agree or disagree when asked to discuss the hot-button issue while having their brain activity monitored using fNIRS.

Source: VLADGRIN/Shutterstock

The researchers report that when two people experience interpersonal agreements during a face-to-face dialogue, both of their brains exhibit a "calm synchronicity" that engages sensory brain areas. Conversely, during a disagreement, higher cognitive processing ramps up and executive functions of the frontal lobes take over. This prefrontal cortex-based monopolization decreases neural activity in social and attention networks involving brain areas such as the right supramarginal gyrus and bilateral frontal eye-fields, the research suggests.

"Our entire brain is a social processing network. However, it just takes a lot more brain real estate to disagree than to agree," lead author Joy Hirsch of Yale School of Medicine's Brain Function Laboratory said in a news release. "There is a synchronicity between the brains when we agree. But when we disagree, the neural coupling disconnects."

"Understanding how our brains function while disagreeing or agreeing is particularly important in a polarized political environment," Hirsch added. "In discord, two brains engage many emotional and cognitive resources like a symphony orchestra playing different music." In agreement, she notes, there's much more social interaction between the brains of two interlocutors that is "similar to a musical duet."

In an era when divisiveness and disagreement seem omnipresent, this research gives us some fresh clues about how cross-brain neural coupling is altered during dynamic verbal exchanges.

Although this research doesn't give us any actionable "how-to" advice on specific ways to increase agreeable and harmonious interactions, it's helpful to have neuroscience-based research that illuminates how engaging in a heated disagreement can alter how our brains work.


Joy Hirsch, Mark Tiede, Xian Zhang, J. Adam Noah, Alexandre Salama-Manteau, and Maurice Biriotti. "Interpersonal Agreement and Disagreement During Face-to-Face Dialogue: An fNIRS Investigation." Frontiers in Human Neuroscience (First published: January 13, 2021) DOI: 10.3389/fnhum.2020.606397