Facebook Friends: The Real Deal or Social Mirage?

3 ways to identify genuine social groups, backed up by recent neuroimaging data.

Posted Mar 31, 2020

Drew Farwell / Unsplash
Drew Farwell / Unsplash
Source: Drew Farwell / Unsplash

The way you think about your online community may say a lot about how socially meaningful they are to you. Recent neuroimaging research shows that we use different brain systems when learning about social vs. nonsocial networks. Here are 3 ways to determine if your group is a bona fide collection of emotionally connected team members or just a social mirage.

1. Communication

Social psychologists often talk about the distinction between “real groups” and collections of people that fall short of true groups—sometimes referred to as “groupings” and “nongroups.” One of the hallmarks of a legitimate group is the quality and structure of communication patterns. A recent neuroimaging study explored the underlying psychology that contributes to social versus non-social network learning. They found that we use different brain systems for those two types of learning.

In the case of non-social networks—for example, understanding the pattern of objects structured in a particular way—we rely on brain regions associated with memory processes.  When we think about social networks—for example, people that communicate emotionally meaningful information to us—we still use the memory systems like with non-social networks. In addition, however, we use brain regions that integrate sensory system information. Basically, when we process content relevant to social communication, we use brain systems designed and dedicated to processing this special kind of information.

2. Size—Yes, There Is a Magic Number

There are limits to the number of people we can cultivate meaningful relationships with, online or otherwise. The magic number, according to British anthropologist Robin Dunbar, is about 150. His theory says that we can realistically maintain approximately 150 connections at once.

The reason stretches far back in our evolutionary past. Based on correlations between primate brain size and social networks, he argued that the brain’s neocortex effectively limits group size. Many of our social adaptations are in tune with small cohesive groups with this capacity. Simply put, we function best in groups of no more than 250 individuals.

How many Facebook friends can you manage without anxiety? According to Omnicore, a digital marketing agency, the average Facebook account holder has 155 friends—consistent with what you would expect following “Dunbar’s number.” In fact, the rule of 150, borne out of our ancestral past, remains true for a vast number of modern groupings: factories, offices, communes, 11th-century villages, military structure, even Christmas card lists.

On average, group size was likely maintained around 100-250 individuals throughout human history. This means that one of our ancestors living 30,000 years ago did not interact with—or even see—more than 250 people in their lifetime. As group size swells beyond 250, it becomes increasingly difficult to keep track of critical social features like who reciprocates, cooperates, and cheats. In Facebook terms, when group size exceeds 250, you find your days filled with stress about keeping up with all the information; or you just give up trying to pay attention to all those lives.

The same logic about group size, however, does not apply to Twitter. Although it is overflowing with personal, emotional, and behavioral content, the process is driven by “following” others instead of mutual friendship. The same goes for Instagram. Note: Facebook does allow users to follow Pages of businesses or brands. For example, the Psychology Today Facebook Page, with over 7.4 million followers, encourages everyone to follow regardless of friendship.

3. Cohesiveness and Identity

A true group is one in which group members get along with one another and identify themselves as being a part of the group. A sports team is an excellent example of a group. In terms of communication, teams cannot function properly without clear signals to each other, both verbally and nonverbally. The roles and hierarchy are explicit as well. Everyone knows the identity of starters vs. backups, captains vs. assistants, forwards vs. defenders, etc. In terms of size, it is never going to exceed 150.

In addition, the most successful groups have members who not only get along with each other but actually like each other. That is why most classrooms do not meet diagnostic criteria for a “true group.” Individual student success is not typically tied entirely to the success of other students. It is quite possible for two students in a course to detest one another and both end up with excellent grades. I have joked with my students that it would be normal to see the entire soccer team out having a meal together after a game, but it would blow my mind if my entire undergraduate social psychology class was doing the same.

In sum, three questions to ask for a quick self-check on your Facebook health are: (1) Are we communicating effectively? (2) Is my group size manageable? (3) Do I actually like these people and do I want to identify with them?

©2020 Kevin Bennett PhD. All rights reserved.


Bennett, K., Gualtieri, T., & Kazmierczyk, B. (2018). Undoing solitary urban design: A review of risk factors and mental health outcomes associated with living in social isolation. Journal of Urban Design and Mental Health, 4:7.  https://www.urbandesignmentalhealth.com/journal-4---solitary-urban-design.html

Dunbar, R. I. M. (1992). Neocortex size as a constraint on group size in primates. Journal of Human Evolution. 22 (6): 469–493. https://doi.org/10.1016/0047-2484(92)90081-J

Tompson, S. H., Kahn, A. E., Falk, E. B., Vettel, J. M., & Bassett, D. S. (2020). Functional brain network architecture supporting the learning of social networks in humans, NeuroImage, 210. https://doi.org/10.1016/j.neuroimage.2019.116498