Figure 2: A sample history of an island is examined and top reproducing robots from two different eras are shown interacting.

From: On The Evolutionary Origin of Symbolic Communication

Figure 2: A sample history of an island is examined and top reproducing robots from two different eras are shown interacting.
Figure 2

The top frame of these behaviour samples shows the trajectory that the two robots take, while the bottom frame shows their communication outputs ωout over time. Auditory interpretations of ωout values are provided in Supplementary Audio S1–S2. An era is 100,000 timesteps. (a) By era 313, indexical communication has emerged. One can determine directly a robot’s absolute y position at a given timestep from its ωout value (y = ωout/4.36, see text). (b) By era 937, symbolic communication has emerged. Robot position information can no longer be determined from observing single ωout values. Instead, relative robot positions are revealed through sign-sign relationships (i.e., by observing both agents’ ωout values, see text). (c) Reproduction rates are shown with (green) and without (grey) communication enabled. (d) Also shown are the magnitudes of the Pearson product-moment correlation coefficients between the position (y in red, x in blue) and ωout of each era’s most reproductively successful agent.