As we have seen in Chapter 2, in most theories involving artificial societies of agents, the
agents are rational (Hogg and Jennings, 1997; Jennings and Campos, 1997), or at least cognitive
(Castelfranchi, 1998). This means that their behaviour is guided by logic rules manipulating
knowledge representations (Shoham and Tennenholtz, 1995).
In this chapter we will see that it is possible to observe intelligent19 social behaviour
without the need of knowledge representation. This is because we will use agents with emergent
cognition, provided by BeCA. We will propose a model where complex social behaviour will
emerge from simple social actions.
4.1. An I&I Model for Social Action20
“I knew they would follow us...”
—Nadia Bazlova
Our model for social action is very simple. It is based in the idea of imitation and
induction (I&I) of behaviours. These will be the only social actions among individuals of a
society. When an individual perceives another individual performing some kind of behaviour,
he might imitate the other if the imitation is beneficial for him in some sense. On the other
hand, an individual will try to induce the behaviour to the other individuals he is perceiving,
who in turn might or might not imitate him. Induction, in this case, is an insinuation for
imitation. An induced behaviour needs to be imitated to be executed by the induced individual.
An imitation would be a weak social action (Castelfranchi, 1998), because the imitating
individual bases his imitation in his beliefs about the behaviour of the imitated individual. An
induction would be a strong social action (Castelfranchi, 1998), because the inducer tries to
make the induced to execute the same behaviour that he is executing.
In animals, most imitated behaviours seem to be reactive behaviours: e.g. flock and
school formations, stampedes, crowd behaviour. But motivated behaviours may also be
imitated. For example, if an animal perceives another one with such a locomotion pattern that
he knows that he is approaching food, if he is hungry, he will follow him, but if he is not,
probably he will not pay attention to the other animal. Another example would be a
Thompson’s gazelle that sees other Thompson’s gazelles speeding her way, presumably fleeing
from a predator. She will not wait until she sees the predator, she will assume there is a
predator coming and flee as the other gazelles. Of course this might lead to collective misbelief.
We can see in animals examples of induced behaviour also. For example, honeybees induce
other honeybees to follow their route to a food source. Some gregarious mammals might warn
other members of their group when danger is near.
19See Section 1.1.1.
20Part of this work was presented in the poster “Action Selection and Weak Social Action” in the Third
International Conference of Complex Systems, in Nashua, NH, May 2000.
55