Pairs of participants played video games requiring communication. Members of a pair were physically separated but exchanged graphic signals through a medium that prevented the use of standard symbols (e.g., letters).

At the beginning of each round of the game, the agents (the little dots, one black and one white) were located in two different rooms at random. The players’ goal was to bring the agents into the same room but limit each agent to a single change of room. If the two agents were not in the same room when players completed their moves, the round was lost. The two agents can communicate via graphic signals only (diplayed on the right of the screen, see the figure), through which they can signal their position, their intention to move, their distination, and so on. However, each player has to guess the meaning of the symbols used by the other player.

Communication systems emerged and developed rapidly during the games, integrating the use of explicit signs with information implicitly available to players and silent behavior-coordinating procedures. How do the players converge? Galantucci explains one method:

Now suppose that on entering room Y, Player A finds the partner there. At this point Player A can conclude that the probability that Player B uses sign S, given that Player B is in room Y, is greater than zero. Although, this information does not yet specify what the sign exactly means (Is S part of a larger sign? Is it about location, or about movement? Is it a request, or a statement?), it offers an opportunity: the player can now use sign S and observe what happens. For example, what is the probability that Player B will end up in room Y after Player A uses sign S?

Note that several systems are possible: (a) systems based on numeration; (b) systems based on the icons in the rooms; (c) systems based on the layout of the game map.

Convergence on a code was not trivial. Most of the pairs took more than one hour to converge, and some of them never succeed. In pair 5, for example, Player B had developed a system whereby the same sign could mean either the agent’s current location or the location the player intended to move the agent toward. Player B seemed not to realize that, without information about which meaning was intended, the signs were ambiguous and often followed the production of the sign for current room by leaving it, miscuing Player A.

Galantucci had run two more complicated experiment in which there are more rooms, a prey, a chasing enemy and a time trial. For those interested, you can explore the different solutions each team have imagined to transformed a code created for a simpler task.

However, the main conclusion of the study is that humans can create a code in less 3 hours, and without a shared environment in which they could point to some objects. They do not need biological or cultural selection of any kind. They are able to evaluate the efficiency of a code by their own. Imagine now what hominians with a theory of mind could have achieved in a whole life of face to face interactions! I have argued, with Hugo, that elaborated cultural norms and institutions could have been created without the modern language we use and only with the help of a theory of mind. These results are consistent with Sperber’s scenario of the evolution of language in which theory of mind appears first, and language second.

Galantucci's exepriments are good news for another experiment of communication without prior coordination nor physical presence.