Washington ? Thomas Schelling, a retired University of Maryland professor, won the Nobel Prize in economics Monday for his application of game theory to issues ranging from global security to racial segregation to the behavior of people stuck in traffic.

Schelling shared the prize with Robert Aumann, of Hebrew University in Jerusalem.

Schelling, 84, of Bethesda, Md., said he had “heard rumors for the last couple of years” but had become convinced that he would not receive the world’s most prestigious prize in economics because of his age.

Asked to describe game theory, he said “it’s the study of how people interact when each person’s behavior depends on, or is influenced by, the behavior of others.”

It departs from conventional applications of economics which traditionally focus on “consumers and producers who take prices for granted and react to them,” he said.

In game theory, he said, “everyone’s best choice depends on what others are going to do, whether it’s going to war or maneuvering in a traffic jam,” he said.

Thus, as he wrote in “Micromotives and Macrobehavior,” horn honking in traffic may seem related to a single reason but upon further analysis, “drivers in traffic start honking their horns … because someone else honked their horn first. Hearing your car horn, I honk mine, thus encouraging you to honk more insistently…. People are responding to an environment that consists of other people responding to their environment,” Schelling wrote, “which consists of people responding to an environment of people’s responses.

“These situations, in which people’s behavior or people’s choices depend on the behavior or the choices of other people, are the ones that usually don’t permit any simple summation or extrapolation to the aggregates…. .We usually have to look at the system of interaction.”

His admirers have credited him with giving them a “new way of thinking” about any number of situations. One reviewer called his approach “logic applied to patterns that are recognizable in real life.”

Schelling and Aumann, said the Royal Swedish Academy of Sciences, have shared a common trait: “an interest in considering aspects neglected by established theory. … A consequence of these endeavors is that the concept of rationality now has a wider interpretation; behavior which used to be classified as irrational has become understandable and rational.”

Schilling’s most prominent book is “The Strategy of Conflict,” published in 1960, which “has influenced generations of thinkers,” said the Nobel committee. The economics sciences prize is awarded by the Bank of Sweden Committee for the Prize in Economic Sciences.

Schilling “was particularly intrigued by the ways in which the parties’ negotiating strength could be affected by different factors, such as the initial alternatives at their disposal and their potential to influence their own and each others’ alternatives during the process,” the committee said in its background material.

In the field of global strategic cooperation, he focused on the “long-run gains a party could achieve by making short-run concessions.”

He “showed that a party can strengthen its position by overtly worsening its own options, that the capability to retaliate can be more useful than the ability to resist an attack, and that uncertain retaliation is more credible and more efficient than certain retaliation,” the Nobel academy said. “These insights have proven to be of great relevance for conflict resolution and efforts to avoid war.”

Aumann, a professor at the Center for Rationality at the Hebrew University of Jerusalem, was cited for his work in looking at how real-world situations can affect the theory.

“In many real-world situations, cooperation may be easier to sustain in a long-term relationship than in a single encounter. Analyses of short-run games are, thus, often too restrictive,” the academy said.

“Robert Aumann was the first to conduct a full-fledged formal analysis of so-called infinitely repeated games,” it said. “His research identified exactly what outcomes can be upheld over time in long-run relations.”