When we interact with others, most of our social energy is directed toward a small group of individuals. We fell almost physically close to them.

Research suggests that the way our brain processes these people differs from how we process those further removed in our social networks, much like how we perceive spaces at different distances.

Our social relationships can be broken into layers, ranging from our closest relationships, like family and friends, to acquaintances. This structure of social layers is similar across different cultures and even non-human animals.

Previous brain research has shown that specific brain regions are activated when we process people from different layers. People closest to us, such as romantic partners, activate a wide range of brain regions, including those involved in emotions and self-awareness. In contrast, acquaintances trigger much more limited brain activity. This suggests that we use different cognitive processes to understand people depending on how close they are to us.

Interestingly, studies have found that the brain processes social and spatial information in similar ways. For instance, we treat close and distant spaces differently in the brain, and this might apply to how we perceive people in various social layers.

Researchers are now investigating how different regions of the brain network respond both to varying levels of social closeness and the different layers of actual physical distance.

The study
In a recent study, researchers explored how our brain processes individuals from different layers of our social networks. To do this, twenty-one participants shared detailed descriptions of their social circles, allowing researchers to create personalized stimuli based on each individual’s social layers. These layers ranged from very close people, such as family and best friends, to more distant acquaintances.

During brain scans, participants were asked to evaluate how "close" they felt to different people in their social network while their brain activity was monitored using functional magnetic resonance imaging (fMRI).

Brain activity was analyzed to identify regions sensitive to various social layers. The results showed that the majority of brain activity, particularly in regions like the prefrontal cortex, was strongly associated with the closest social layer (the support clique).

In contrast, more distant social layers activated different brain regions, including areas in the hippocampus. These findings were supported by statistical analyses, confirming a clear division in brain activity between the closest and more distant social layers.

Further analysis of brain networks revealed that the default mode network (DMN), involved in self-reflection and social cognition, played a central role in processing social closeness. Specifically, the network was more involved in processing the closest social layer.

Interestingly, the study also found that brain regions involved in processing social closeness overlap with those that handle physical distances. For instance, brain areas linked to processing small spaces, such as a room or house, were active when processing the closest relationships, while larger spaces, like a city or country, were engaged when thinking about more distant social layers.

This suggests that our brains treat both social and physical proximity in similar ways, reinforcing the connection between how we perceive relationships and our surroundings.

How the Brain Sees Social Closeness
This study explores how the brain processes individuals from different levels of closeness in our social network. The brain's activity related to the closest social circle, or support clique, was concentrated in specific regions, which are involved in processing personal experiences and emotions. In contrast, distant relationships activated different brain areas, often linked to memory and broader cognitive processes.

The findings also suggest a surprising similarity between how the brain processes social proximity and physical distance. This division points to a shared cognitive principle where the brain organizes both social and spatial distances in a similar way.

About the scientific paper:

First author: Moshe Roseman-Shalem, Israel
Published: Nature Communications Biology, October 2024.
Link to paper: https://www.nature.com/articles/s42003-024-06934-8