  We study what are the factors that can accelerate the emergence of
collaborative behaviours among independent selfish learning agents. We depart
from the "Battle of the Exes" (BoE), a spatial repeated game from which human
behavioral data has been obtained (by Hawkings and Goldstone, 2016) that we
find interesting because it considers two cases: a classic game theory version,
called ballistic, in which agents can only make one action/decision (equivalent
to the Battle of the Sexes) and a spatial version, called dynamic, in which
agents can change decision (a spatial continuous version). We model both
versions of the game with independent reinforcement learning agents and we
manipulate the reward function transforming it into an utility introducing
"loss aversion": the reward that an agent obtains can be perceived as less
valuable when compared to what the other got. We prove experimentally the
introduction of loss aversion fosters cooperation by accelerating its
appearance, and by making it possible in some cases like in the dynamic
condition. We suggest that this may be an important factor explaining the rapid
converge of human behaviour towards collaboration reported in the experiment of
Hawkings and Goldstone.
