Schelling Segregation
Two groups of agents (gold and blue) share a grid with empty cells. An agent is unhappy if fewer than the threshold fraction of its neighbors share its type, and moves to a random empty cell. Even mild preferences produce dramatic macro-level segregation.
About this lab
In 1971, economist Thomas Schelling published a landmark paper showing that residential segregation can emerge even when no individual agent is strongly prejudiced. In his model, agents of two types share a grid. An agent is satisfied if at least some threshold fraction of its neighbors share its type; otherwise it moves to a random empty cell.
The striking result is that even a threshold of 30% — meaning an agent is happy as long as fewer than 70% of its neighbors are of the opposite type — leads to nearly complete segregation over many rounds. The macroscopic outcome (strong segregation) is far more extreme than the microscopic preference (mild preference for similarity). This illustrates how emergent social patterns can diverge dramatically from individual intentions.
The segregation index shown here measures the fraction of each agent's neighbors that share its type, averaged across all occupied cells. A value near 50% indicates random mixing; values near 100% indicate strong segregation.