Neuroscientists uncover a fascinating fact about social thinking in the brain

When we think about people in our social circle, our brains appear to keep track of two different kinds of comparisons: how others relate to each other, and how others relate to ourselves. A new study published in Psychological Science shows that these two types of social knowledge—called allocentric and egocentric similarity—are represented by entirely different brain systems. Using functional brain imaging and a unique design involving real-world social groups, the research reveals that the brain independently processes these reference frames when we consider the traits of people we know.

Prior research has shown that people are quick to form impressions of others and often rely on perceived similarities—either between others or between others and themselves—when navigating social relationships. But it was not clear whether these two types of comparisons are computed by the same brain mechanisms or whether they rely on separate systems. Drawing inspiration from spatial cognition, where scientists distinguish between allocentric (object-to-object) and egocentric (self-to-object) frames of reference, the researchers aimed to test whether similar distinctions exist in how we mentally represent people.

“When we are driving a car down the road, we need to how both far we are from an upcoming car but also how close that car is from other cars next to it,” explained study author Robert S. Chavez, an associate professor in psychology and the Center for Translational Neuroscience at University of Oregon. “In other words, it needs to know the self-to-other distance (egocentric distance) and the other-to-other distance (allocentric distance) to drive safely. There had been previous work on how the brain processes these reference frames in spatial cognition, but we were inspired to see if the brain processes social information using similar processes.”

To explore this, the researchers recruited 108 participants from 20 real-world social groups, such as student clubs, coworker teams, and friend groups. Each group consisted of six people who were familiar with one another. The study used a round-robin design in which every participant rated themselves and each other member of their group on traits related to warmth (e.g., friendliness) and competence (e.g., effectiveness). These ratings were used to construct models of allocentric similarity (how similar group members were to each other) and egocentric similarity (how similar each person was to themselves compared to others).

In a separate session, the same participants underwent functional magnetic resonance imaging (fMRI) while completing a trait-judgment task. During the task, they were shown names of themselves or their peers along with descriptive words (like “happy” or “clumsy”) and asked to decide whether the trait applied to the person. This task was designed to elicit neural patterns reflecting mental representations of each individual. The researchers then used statistical modeling to compare how similar the brain’s responses were when participants thought about each peer and how that matched up with the behavioral similarity ratings.

The key finding was that both allocentric and egocentric similarities were reflected in brain activity patterns—but in completely different sets of brain regions. Allocentric similarity was associated with increased neural similarity in areas such as the ventromedial prefrontal cortex, posterior cingulate cortex, and lateral orbitofrontal cortex.

These regions have previously been linked to social cognition and are part of the brain’s default mode network, which is active when we think about other people or ourselves. Notably, these regions also overlap with those involved in spatial navigation using allocentric reference frames, supporting the idea that the brain may repurpose spatial mapping systems for social mapping.

In contrast, egocentric similarity was associated with neural activity in the dorsal medial prefrontal cortex and anterior cingulate cortex—areas involved in social comparison, self-other distinctions, and mentalizing.

“When we think of other people, our brain spontaneously represents information about both the similarities among others in our social world as well as our position in that similarity space,” Chavez told PsyPost. “Our results show that how these similarities are computed is carried out in independent brain systems at the same time. Just like the example of a car driving down the road, we need both of these calculations to make sense of complex social information.”

Interestingly, the relationship between perceived similarity and brain response went in the opposite direction: the more similar participants thought someone was to themselves, the more dissimilar their brain patterns were when thinking about that person. This suggests that the brain may actively maintain a distinction between the self and others, even when those others are perceived as similar. This kind of neural separation could help prevent confusion between our own thoughts and those of others, especially in socially close relationships.

“One finding that might surprise some folks was the finding that greater the closer people were in egocentric similarity, the more dissimilar their brain responses were in the dorsal medial prefrontal cortex which is often implicated in mentalizing and processes related to empathy,” Chavez explained. “We think this is interesting because it dovetails with theories on the need for cognitive separation between self and others that may help facilitate.”

Another important aspect of the study was the comparison between individual ratings and group consensus ratings. The researchers tested whether the average ratings of each person by the group better predicted brain responses than the individual’s own ratings. Across the board, they found that within-perceiver ratings were more closely aligned with neural patterns than group-averaged ones. This suggests that how a person personally evaluates others—even if biased—is more consistent with their brain’s internal representation than how others see those same people.

The study’s results provide strong evidence that the brain uses distinct systems to encode different kinds of social similarity. Allocentric and egocentric reference frames were associated with nonoverlapping brain regions, supporting the idea that they are processed separately rather than as part of a single, unified social-evaluation system. This finding helps clarify long-standing debates in the field about whether different types of social information are handled by shared or separate neural mechanisms.

Although the study sheds new light on how the brain encodes different types of social similarity, it also has limitations. The sample consisted mostly of young adults from a university setting, many of whom were White and middle-class. As such, the findings may not generalize to people from other backgrounds or to different types of social relationships, such as family members or long-term romantic partners. The task also involved relatively passive trait judgments, which might engage different processes than more interactive or emotionally charged social experiences.

“It is important to remind ourselves that these subjects are lying on their back in a noisy tube (the MRI machine), which is about the most non-social place in the world,” Chavez noted. “Although we think these results speak to the way the brain processes social information, it clearly cannot capture the richness of these processes in the real world.”

Future research could explore how these brain systems function in more diverse groups and during more natural social interactions. The researchers also plan to investigate how these patterns longitudinally, particularly as relationships change and evolve. Another promising direction is to examine how social reference frames are affected in conditions where social processing is impaired, such as in autism or certain personality disorders.

“We are hoping to continue to use real-world groups of people in combination with more naturalistic stimuli and methods to address some of the limitations of this study and provide even more detailed understanding about how the brain represents dynamic information about the relationship between self and others and how this unfolds over time,” Chavez said.

The study, “Person Knowledge Is Independently Encoded by Allocentric and Egocentric Reference Frames Within Separate Brain Systems,” was authored by Robert S. Chavez, Taylor D. Guthrie, and Jack M. Kapustka.