Why Does Society Divide Itself Into Smaller Categories of People Over Time? (In-Group and Out-Group Formation)


We are born without prejudice.

Ask a baby if he hates any particular person and he will stare at you, blink occasionally and eventually (as is the norm for someone his age) burst into tears –not because of a profound distaste for the idea of hatred- but because of a need for food, security or toiletry. Babies are unique in viewing all humans as equal.[1] They are the only humans who have yet to learn the complexity of social structures, race and other forms of social categorisation. To them we are all the same, and the idea of creating a hierarchy of people they meet has yet to cross their mind. Or, more accurately, has yet to be taught to them.[2] Prejudice in its true form, only begins at age 3.

Make a silly face to a baby in the street and regardless of whom you are or your relationship to them they will laugh. Their parents however will have one of two reactions. If you look like an upstanding member of society -albeit while contorting your face- they will laugh with their child. If  you fit into their criteria of people they shouldn’t talk to, they will glare at you in disapproval and turn away.

An evolution has occurred between these two stages of life.

This is the story of that evolution.

In preschool we remain largely free from prejudice and associate with anyone who crosses our path – giving them the opportunity to impress us with their personality traits and skills before passing judgment on them in the ultimate sense: deciding whether to befriend them. At this very young age, we choose friends not by predetermined characteristics or social status, but often by random and accidental mutual enjoyment of activities – computer games, sports, pranks etc.[i] The main requirement for friendship at a young age is a shared interest in a common activity. A child that enjoys sport, for instance, is a potential friend of another sport-loving child.

Unless taught to do so, our choice of friends is not influenced by religion or social status. There is admittedly a tendency for pre-school friendships to develop on the basis of age (the environment hardly provides opportunities to befriend older students) and for friendships to develop between children of the same sex more than between sexes, and between the same races – because colour as a categorical tool on a very basic visual level is hard for even toddlers to avoid using (unfortunate as it is, this can be avoided by grouping toddlers of different races together in pre-school groups – to foster mutual respect and understanding, and to begin the process of realizing that colour is no actual barrier to similarity).[ii] The reference to sex may be a cultural expectation; boys are expected to befriend boys and girls to befriend girls, because romance is strictly prohibited in youth. Aside from age, race and gender, the criterion of ‘common interest’ is a very broad one. By befriending those who  share a “common interest” we are not limited to segmentations of: demographic, social status, religion and so on. In this way, we are likely to mingle with a diverse range of children from a diverse variety of backgrounds.[3]


During the beginning of high school a shift in priority takes place. Having developed a greater, well-rounded sense of identity and a more thorough understanding of the differences between different groups, we start to make more complicated and predetermined decisions about whom to befriend. While once we required JUST a shared activity, now we require much more: similar personalities, shared belief systems, similar tastes in music, film, demographic backgrounds, social status, clothes etc.[iii] Of course we do not require ALL of these similarities, all at once, but as we age the importance of each similarity increases, and we start choosing their friends based on some or all of these criteria. The end of High School is the epitome of this process. Clear social circles are formed. Groups or “cliques” form around shared interests, beliefs, social statuses, race, gender and other social categories.


At university a final and all-important category – career aspirations – is added to the list. The variety of people we meet diminishes markedly. Not only because of the grades required to get into university (and thus the requirement of academic intelligence), but also the choice of a single degree. Limited to classes within your own degree, you are limited to making friends with other people who share your career aspirations, academic interests and occasionally, outlook in life. Studying finance allows you to meet students with an interest in the financial field. Studying law allows you to meet other students interested in law, politics, international relations and other “language-heavy” professions. So the process goes on.

In the working world we are often limited to making friends within the same industry or related sub/parallel industries. Investment bankers become friends with other investment bankers and those in financial and banking industries. The same is generally true of other professions. This creates a narrowing of perspective and culminates in the social groups of high school forming on a much larger scale. Instead of social circles clustered around lunch tables, employment circles come to dominate entire suburbs. A “bubble culture” develops whereby corporate types associate with other corporate types in corporate suburbs. The artists flee to their own enclaves. This process culminates in the self-imposed ghetto, a system whereby suburbs are defined and characterised by the people who live there.

The process is cemented by networking. In the workplace, priority is given to conversations with those in the same or related industries because these conversations have the potential to facilitate promotion or career advancement. By consequence, we sacrifice conversations with those in unrelated industries who cannot give us these same tacit financial rewards. As a result, we befriend those with similar career aspirations, or those on the same ‘ladder’ as us, rather than those on different ‘ladders’.

The above developmental process results in the ultimate narrowing of the human experience. The diversity of people we meet diminishes markedly as our lives develop. As we grow older, we move closer and closer to forming friendships and relationships ONLY with people in our own ‘category’ of society, rather than diverse “other” categories. We form cities with boundaries and social circles “firmly closed against neighbouring, strange, or in some way antagonistic [other] circles.”[iv] This culminates in a situation where everybody we know is intrinsically similar and not well placed to challenge our perceptions of the world around us. Instead of social cohesion, we have social isolation. Instead of diverse and intermingling communities, we have community ghettoes.


Why Does This Process Occur?

By the time we become adults we have a greater appreciation of the categorical distinctions between us. We have been taught, through the education system and the people around us, that people belong to different groups, and that these different groups are intractable and unchangeable. It is therefore not too surprising that when we meet people we immediately define them by their; race, occupation, hobby, income, demographic and personality. By having pre-existing categories in our back pocket, we can “already tell” if we’re going to get along with them: all we have to do is judge the ‘category’ they belong to, and compare it to our own. If they belong to our own category, we’re more likely to become friends with them.

The reason why we’re more likely to become friends with people in our own ‘category’ is founded in the social psychological principle: “Similarities Attract”. The evidence shows there is a broad psychological tendency for us to associate more with those who are similar to us, rather than those who are dissimilar.[v] This appears in friendships and romantic relationships (although the evidence is stronger for romantic relationships).[vi] We are attracted to, and tend to like, and spend more time with, those who are similar to us. Similarities can be in physical characteristics, but also in demographic features like age, race, sex, income etc.[vii]


While this principle is rock solid science, it is important to note that the ‘similarities’ we talk about are often social constructs. To use a trite example: I am only similar to other Australians, so long as the term “Australian” exists as a categorical distinction between my country vis a vis the rest of the world. If there was no word for “Australian”, I would not be able to claim that nationalistic similarity with other Australians. So when we say people are “similar” to us, we are often saying that they belong to the same category. But the categories we talk about are inventions of the English language. In this way the language we use defines us, and those around us, by making us categorically different from one another. We then make friends in these categories, driven by the “similarities attract” principle. This leads to a narrowing of our relationships as we age, which results in us mainly being friends with people who are, in one way or another, similar to us.

The idea that “opposite attracts” has been largely disproven.[4][viii] In a romantic sense and in friendship the evidence goes against the idea that we are drawn to, or tend to like, people who are different to us.[ix] While we might individually consider our partners and friends to be ‘nothing like us’, when given a larger amount of thought and consideration, often we do in fact share a core set of similarities and traits between us and our loved ones.

On the other hand, if we are in fact substantially “different” to a spouse or friend, it may be that we have formed our relationship due to close physical proximity, itself a form of ‘similar’ experience. Indeed social psychology evidences the idea of propinquity, similar to the “exposure effect” – the more we are exposed to a person, the higher the chances we will form a friendship or close romantic relationship with them. This is one explanation as to why friendships and romantic relationships tend to develop in high school, the workplace and other environments where exposure occurs over a prolonged period of time. A study of college students found that students were “10 times more likely to become friends” with others cohabiting “in the same building”, rather than those in neighbouring or distant buildings.[x]


Physical proximity gives us the opportunity to get to know someone. Admittedly, it could allow us to dislike someone much more than we otherwise would. By being close to someone, we get to know the things we like and dislike about them.[xi] However, even if this occurs, we are gaining an opportunity to understand them. The risk of disliking someone is worth it in this sense. Mutual understanding is an end goal in its own right. Regardless of liking or disliking someone, if we understand them then we can at least begrudgingly accept the motivations behind their actions. Indeed, the common phrase “familiarity breeds contempt” is only occasionally true. Generally familiarity “breeds liking”.[xii] We tend to like those we see often. Just by facial recognition alone we can “like” someone or become predisposed to becoming friends with them.

The truly incredible thing about physical proximity is that it lets us overcome our natural inclination to befriend only those “similar” to us. If we are constantly in contact with someone of a different race, gender, age or demographic there is evidence to suggest a friendship can still develop. But in the absence of close physical proximity we have a tendency to ‘seek out one of our own’. When we have the choice, and the lack of constant contact, we tend to choose “similarity” over difference, and we tend to befriend only those similar to us, and only those belonging to our own ‘tribe’.

A modern example is the way in which Australians treat refugees, or “boat people”. ABC’s Vote Compass (2013) revealed that those with a higher exposure to refugees in close physical proximity (within their suburbs) were more likely to welcome refugees into their community.[xiii] By contrast, those living in rural areas, that tended to lack refugees in previous decades, and therefore lacked that requisite physical proximity, were less likely to welcome refugees. Those in rural areas were supportive of the “Stop the Boats” policy to reject refugees. By contrast, those in close physical proximity with refugees went the opposite way, and tended to support the inflow of further refugees. This suggests that communities are more accepting of diversity, if they are already diverse. Pre-existing physical proximity can overcome the urge to reject others on the basis of xenophobia. It can overcome our urge to stick to “one of our own”.


We gain a mutual respect and understanding of others if we live near them; we gain xenophobia if we live in isolated communities.


We can use the above ideas of physical proximity to overcome our natural urges to seek out ‘one of our own’ and foster communities that are more diverse and inclusive by nature – of both outsiders and insiders alike. Instead of narrowing the type of people we interact with as we grow older, we can expand our interactions, by setting up physical situations where it is easier to interact with those who are “different” to us. By bringing disparate groups into the same space, we can foster mutual understanding, empathy and in some cases friendship. This could mend some of the categorical division that exists in our society. Over time, if we bring people together, we could unite behind a common understanding of humanity. By doing so we could end categorical prejudice and segmentation.

 This is an extract from my book: Us vs Them: A Case For Social Empathy”.

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[1] Discounting their parents, whom they idolise.

[2] Admittedly, there is a from-birth predisposition towards people with symmetrical faces. This is a precursor to physical attraction.

[3] Admittedly parents do limit this process by placing children in schools with certain characteristics (religious schools, private schools and specialist schools of sport, dance or music).

[4] With the exception of dominant/submissive opposites of control, particularly in organisations as between employers and employees.

[i] Kelly A. McNamara, ‘The Company They Keep: Homophily in preschool relationships’, University of Kansas (Thesis) (2007).

[ii] W. W. Hartup, ‘Social relationships and their developmental significance’, American Psychologist, (1989), 44(2), 120-126.

[iii] D.B. Kandel, ‘Homophily, selection, and socialization in adolescent friendships’, American Journal of Sociology (1978a), 84(2), 472-436;

D.B. Kandel, ‘Similarity in real-life adolescent friendship pairs’, Journal of Personality and Social Psychology, (1978b), 36(3), 306-312;

French et. al, ‘Friendships of Indonesian children: Adjustment of Children who Differ in Friendship Presence and Similarity Between Mutual Friends’, Social Development (2003), 12(4), 605-621;

G.J. Haselager et al, ‘Similarities between Friends and Nonfriends in Middle Childhood’, Child Development (1998), 69(4), 1198-1208.

[iv] George Simmel, ‘The Metropolis and Mental Life’, The Sociology of George Simmel, Kurt Wolff (Trans.), (New York: Free Press, 1950), p. 409-424.

[v] Newcomb, T.M, “Stabilities Underlying Changes in Interpersonal Attraction”, Journal of Abnormal and Social Psychology (1963), 66, 376-386;

Byrne D, “Interpersonal Attraction and Attitude Similarity, Journal of Abnormal and Social Psychology, (1961), 62, 713-715;

Schneider, B., Goldstein, H. W., & Smith, D. B. (1995). The ASA framework: An update. Personnel Psychology, 48, 747–773;

“When Similars Do Not Attract: Tests of a Prediction from the Self-Expansion Model”, Personal Relationships, 13 (2006), 387-396.

Umphress, Elizabeth E; Smith-Crowe, Kristin; Brief, Arthur P.; Dietz, Joerg; Watkins, Marla Baskerville, “When Birds of a Feather Flock Together and When They Do Not: Status Composition, Social Dominance Orientation, and Organizational Attractiveness”, (2007), 92(2), p. 396-409

Douglas W. Nangle, Cynthia A. Erdley, Karen R. Zeff, Lora L. Stanchfield and Joel A Gold, Opposites Do Not Attract: Social Status and Behavioural Style Concordances and Discordances Among Children and Peers Who Like or Dislike Them, Journal of Abnormal Child Psychology, 32, No. 4 (2004), p. 425-434

[vi] Umphress, Elizabeth E; Smith-Crowe, Kristin; Brief, Arthur P.; Dietz, Joerg; Watkins, Marla Baskerville, “When Birds of a Feather Flock Together and When They Do Not: Status Composition, Social Dominance Orientation, and Organizational Attractiveness”, (2007), 92(2), p. 396-409

[vii] Douglas W. Nangle, Cynthia A. Erdley, Karen R. Zeff, Lora L. Stanchfield and Joel A Gold, Opposites Do Not Attract: Social Status and Behavioural Style Concordances and Discordances Among Children and Peers Who Like or Dislike Them, Journal of Abnormal Child Psychology, 32, No. 4 (2004), p. 425

[viii] Berscheid, E., & Reis, H. T. (1998). Attraction and close relationships. The handbook of social psychology, 4th edition, 193-281.

[ix] “When Similars Do Not Attract: Tests of a Prediction from the Self-Expansion Model”, Personal Relationships, 13 (2006), 387-396.

[x] Festinger, L., Schachter, S., & Back, K. Social pressures in informal groups: A study of human factors in housing (Harper: 1950);

Miles Hewstone, Wolfgang Stroebe & Klaus Jonas (eds.), An Introduction to Social Psychology (BPS Blackwell, 5th Ed, 2012), p. 368.

[xi] Miles Hewstone, Wolfgang Stroebe & Klaus Jonas (eds.), An Introduction to Social Psychology (BPS Blackwell, 5th Ed, 2012), p. 368.

[xii] Ibid; Moreland, R.L. & Beach, S. R. ‘Exposure Effects in the Classroom: The development of affinity among students’, Journal of Experimental Social Psychology, (28), 255-276.

[xiii] Paul Syrvet, ‘The ABC’s Vote Compass reveals sunburnt necks of voters in the Sunshine State’, The Courier Mail (September 03, 2013) <http://www.couriermail.com.au/news/opinion/the-abc8217s-vote-compass-reveals-sunburnt-necks-of-voters-in-the-sunshine-state/story-fnihsr9v-1226709281069>;

‘Vote Compass: Kevin Rudd’s Asylum Seekers Policy Divides Labor Faithful’, ABC News (21 August 2013), <http://www.abc.net.au/news/2013-08-21/asylum-seekers-vote-compass-boats-immigration/4899914>


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