Figure 1 : NoiseWorld.

From: On The Evolutionary Origin of Symbolic Communication

Figure 1

Robots exist in a 2D world and can sense their own x and y locations. They cannot sense any information about their neighbours. Robots can produce nondirectional sounds ωout and can detect the sounds produced by their nearest neighbour ωin. Robots live on one of the islands in the world, and when two robots meet, they automatically produce one offspring. A randomly selected robot dies whenever a new offspring robot is born. Islands are organized in a toroid. Offspring robots are occasionally born on one of the four neighbouring islands.