In 1963, he was invited to a summer institute at the RAND Corporation in Santa Monica, Calif., to trade ideas about modeling cognitive processes using computers. While there, he began developing his own computing toolbox for social scientists, calling it DYSTAL. A 1971 paper, “The Checkerboard Model of Social Interaction,” modernized his 1949 model through computer-run simulations.
After retiring from Brown in 1981, Sakoda told Hansen, “I think the best thing I’ve done is the social interaction model, which solved the problem in social psychology of going from the individual level to the group level.”
But in the 1990s and 2000s, as agent-based modeling became fundamental to studying infectious diseases and the movements of humans on a large scale, a different origin story emerged.
Thomas Schelling, a well-connected Harvard economist and White House adviser, was on a plane bound for Boston when he started noodling with Xs and Os moving along a line. It would eventually become a checkerboard model strikingly similar to Sakoda’s. Schelling mentioned it in a 1969 RAND research report and expanded it into an article in 1971, shortly after Sakoda had published his, in the same journal.
Decades later, it was Schelling’s article that became widely credited as the first in which the checkerboard model appeared.
It is possible that Schelling encountered the seed of the idea at RAND — he completed a residency there a year after Sakoda visited. But when asked in a 2001 interview if the checkerboard model devised by Sakoda had influenced him, Schelling replied, “I have never heard of him.”
In 2005, Schelling was awarded the Nobel Prize in economics, with Robert J. Aumann, for “having enhanced our understanding of conflict and cooperation through game-theory analysis.” In a biographical statement accompanying the prize, Schelling wrote of the checkerboard model, “Without knowing it I was pioneering a field of study that later became known as ‘agent-based computational modeling.’”