Gaming The Population

            There is a good chance that over the holiday period many of us will have indulged in one or more games with our relatives and friends. The aim of the standard board games or card games is normally to be the sole winner, although some games require cooperation such as Save the Whales, Pandemic or Max.

The game theorists are into other sorts of games, which delve more into our psyche. One of their favorites is the Prisoners Dilemma game in its iterative version. In case you’ve forgotten the game, it’s very simply the situation beloved of the writer’s of police dramas. There are two prisoners. Each has the choice of sticking to a prior agreement to say nothing, in which case they both get one month in jail. If one defects and rats out the other, he/she walk free and the other gets a year inside.

We should note that if each rats on the other, they both get three months in jail. The logic goes that during iterative play, the players both become defectors and cooperation is an unstable condition.

Those with large computers to hand don’t have to troll round their police stations or student bars to find real players, but can do this with simulations of large populations. Wang, Han and Han at the Chinese Academy of Sciences in Beijing are among the most recent to try a variation (1).

Their simulation used a large population in which everybody could interact, but any pair only play each other once. They showed that a population that started out with 50% of the population trying to be cooperative rapidly turned into one with only about 15% trying to be cooperative. This was the baseline.

The fun began when they stuffed stooges into the mix who were instructed to cooperate if the other players record indicates that they are probable cooperators, otherwise they defect. The governors of the game only make the opting records of the players available to their stooges.

The addition of stooges was termed “soft control” and if there were a significant number of stooges in the population, more cooperation was the result. The amount of cooperation was a function of the number of stooges, though a large number are required to make a large difference.

Other variants have been reported with additions to the population of agents who can add feedback, or teaching, to the population, but this would be a form of “hard control”. Soft control is taking place without the population realizing it in the case studied here and, of course, our Ad Agencies are already aware of its effectiveness.


Please note that this blog is migrating to
in 8 days.

Leave a Reply