Complete segregation emerges even when individuals only mildly avoid being a minority

Evidence

In one of the earliest applications of ABM in the social sciences, Schelling (1971) examined how segregation between social groups can arise through the actions of individual agents, even when no agent specifically desires segregation. Schelling’s model assumed that each agent used a single, simple rule: do not be in the minority in your neighborhood. To implement the model, agents moved to random empty spaces if the proportion of “in-group” agents surrounding their current space fell below a certain threshold, such as 50%. The rule was applied until all agents stopped moving, settling into their spaces. The final result, which occurred under a wide range of moving thresholds, was almost complete segregation among the agents, with clear group boundaries. This model was important because it offered the counterintuitive conclusion that extreme segregation may inevitably result from the extended interactions and choices of individuals who do not necessarily desire extreme segregation. The model also makes clear that such an outcome does not require the intervention of a central, organizing agency (e.g., real-estate agents) in order for segregation to occur, but rather may emerge in a self-organized fashion from individual-level motives. Finally, the model was important in demonstrating the significance of an agent’s definition of neighborhood. When agents were programmed to define their neighborhoods narrowly, segregation was a very likely outcome. In contrast, if agents defined their neighborhoods more broadly (e.g., the whole population of agents in a wider region—a city vs. a neighborhood), extreme segregation was far less likely. — Roderick M. Kramer, Geoffrey J. Leonardelli, Robert W. Livingston, Social Cognition, Social Identity, and…, 824

Categorization

• XREF: Core corroboration/complication for the reading purpose: macro-level segregation can arise without strong individual prejudice, complicating any direct line from individual ingroup affect to structural outcomes. — connects to: Small residential minority increases greatly amplify into public school resegregation — Kevin M. Kruse, White Flight: Atlanta and the Making of…, 588; Segregated space silently perpetuates stratification even with no active racists; Segregation can perpetuate itself silently with no active racist actor — Luke W. Cole and Sheila R. Foster, From the Ground Up: Environmental…, 343 (+3 more)
• QUESTION: The neighborhood-definition finding is intriguing — does this scale to how prejudice research defines ‘group contact’ or ‘proximity’?
• ADDENDUM: Connects to the trees-as-infrastructure grafting essay only loosely; more directly feeds the prejudice-psychology thread the reader is reconstructing.
• corroborated: 2 independent passages support this claim — Roderick M. Kramer, Geoffrey J. Leonardelli, Robert W. Livingston, Social Cognition, Social Identity, and…, 824