At Growth By Design, we believe intentional choices lead to impactful growth, whether you’re shaping a thriving organization or a meaningful life. Here, we provide the practical information, tools, and frameworks to get you there. Today we’re diving into a crucial and sometimes uncomfortable truth: how your brain is constantly categorizing people into “us” versus “them”, and the profound effect this has on your life.

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What Are In-Groups and Out-Groups? The Basic Psychology Behind Belonging

Social psychologists define an in-group as any group you identify with – family, culture, workplace, sports team, or even a book club. By contrast, an out-group is the group you don’t belong to, and often see as “other.” Henri Tajfel’s groundbreaking research in the 1970s cemented these terms in our vocabulary, showing that people will form strong group identities in mere minutes and start preferring their own group, even when it’s defined by random chance. From schoolyard cliques to global politics, the in-group/out-group split is everywhere.

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“It suggests that people seek to enhance their self-esteem by identifying with in-groups and differentiating from out-groups.“

– Social Identity Theory, Tajfel & Turner (1979)

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We’re glossing over really big concepts here that drive our every day interactions, which in turn shape our society. If this concept is new to you, I invite you to dig into this a bit more – here is a great short video that shows how our brains respond to in-groups and out-groups.

A Glance At Our Deep Psychological Wiring for “Us” vs “Them”

Research finds that social identity is a core part of self-esteem. We boost our group because it makes us feel secure and valued. This impulse is so strong, we’ll find tiny, even arbitrary distinctions and turn them into meaningful divides. Our brains are wired to love “us” (yes, even if you perceive yourself as having low self-esteem) – and be wary of “them.” Studies suggest this mechanism is not just social, but neurological, affecting how we process information, distribute empathy, and even how our brains reward us for acting against the out-group.

This 2016 National Library of Medicine research paper found people persistently favored in-group members – even when it made little logical sense – and were hostile to out-group members, often denying them positive attributions. Further, recent AI empathy studies even show language models absorb and mirror this bias, assigning higher empathy to their own “group”.

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“In-group members are perceived as having positive qualities. Out-group members are viewed more negatively, and receive inferior treatment.“

– Social Categorization Research

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Why Is It Harmful? The Real-World Pitfalls

It is nice, and unavoidable, to like having commonalities with others! We fundamentally like people who are more like us – be it shared interests, demeanors, goals, etc. But here’s where it gets tricky – and harmful. In-group/out-group dynamics can lead to:

• Empathy gaps: Even artificial intelligence inherits real human group biases, showing less empathy toward “outside” groups.
• Aggression is rewarding: fMRI studies reveal some brains feel literal pleasure from excluding or harming out-group members – explaining why conflict between groups is so sticky.
• Reduced opportunity: Workplaces with in-group/out-group cliques report higher turnover, lower innovation, and greater employee dissatisfaction.
• Cliques and exclusion: Marginalized “outsiders” feel isolated, leading to higher anxiety, turnover, and limited career growth. At its most extreme, this is the basis of racism, misogyny, and hate. At its most covert, this looks like micro-aggressions that signal to others they are in fact “other” and unwelcome.
• Groupthink: Cohesion can suppress dissent, which stifles creativity and causes bad decisions (You know that feeling that isn’t said but often felt, “We just go with the group, even when it’s wrong.”).
• Bias and discrimination: Stereotyping, scapegoating, and even aggression towards out-groups are common human behaviors. Studies show the brain experiences literal reward when harming out-group members, because it strengthens your justification for the superiority of your ‘in-group’ / “us”.
• Reduced empathy: Research finds empathy gaps – people are less likely to feel compassion for, or help, those they see as outside their group, regardless of context.
• Societal polarization: On a large scale, this dynamic fuels prejudice, conflict, and persistent injustice. On a small scale, this fuels gossip, friction, and a lack of meaningful relationships.

For my fellow millennials – in-group and out-group can be perfectly summarized by this iconic moment in Mean Girls (well, really the whole movie):

Practices and Prompts I Use to Help Me Notice (and Avoid) This in Myself

If in-group / out-group is our neurological default, how can we hack our brains to treat more people as “us” versus “them”? I am on a journey to find this out. What I have found helpful in digging into this concept deeply in my PhD was to learn how to spot and shift these patterns.

Here are a few prompts I work to intentionality use daily before, during and after interactions to get my mind in the right frame:

1. Who is someone who really grates on me? Why do I feel this way and what identity in myself am I trying to protect?
2. Who do I interact with easily, and who do I avoid? What signals am I sending – intentionally or not?
3. What is a behavior in someone else that I am harsh to judge? What story do I tell myself about why they behave this way? What else could be true? (as a chronic early arriver, lateness is something I judge quickly!)
4. In what ways do I show up that help others see me as part of their in-group or out-group?
5. When I feel defensive, what group identity am I protecting? How does it affect my response?
6. When was the last time I listened, learned from, or collaborated with someone totally outside my usual circles?
7. How do I make space in my life or team for people not in ‘my group’ to contribute and belong?
8. If someone I perceive as an out-grouper challenged my perspective, would I listen or shut down? Why? How does this stifle my growth?

Join Me in Building More “Us” and Less “Them”

I’ve come to accept that in-groups and out-groups are part of what it means to be human, but I am unwilling to accept that we as humans are not smart enough to learn better. But the most resilient, creative, and compassionate lives – and teams – are built by noticing these patterns, and intentionally bridging divides. When you design a relationship structure that is built for belonging, you invite new perspectives, spark true innovation, and create a space where everyone can thrive.

So friends, I invite you to join me on a lifelong journey of moving beyond “us” vs. “them” – and choose each day to see each other as more similar than different.

Onward and upward!
Katie