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In-Depth Information
Fig. 12.
Synchronisation speed of the dyad, depending on the Agent2 understanding
u
2
and initial
phase-shift
Δφ
ini
(
σ
=0
.
05 and
β
=0
.
7).
u
2
varies between 0 and 0
.
02.
Δφ
ini
varies from
0 to
π
. When the synchronisation speed value is null, the dyad did not synchronised until the
end of the experiment. A synchronisation speed 1 is for a synchronisation occurring at the very
beginning of the experiment.
levels of understanding
u
1
and
u
2
do not differ more than
15%
of each other, they
synchronise systematically and very quickly: for instance they synchronise even when
they start in anti-phase (
Δφ
ini
=
π
). And conversely, when the levels of understanding
u
1
and
u
2
are more than
15%
different, synchronisation is no more immediate.
4
Discussion
We proposed and tested a model which links emergence of synchrony between dialogue
partners to their level of shared understanding. This model assesses both the understand-
ing of humans and the believability of artifacts (e.g. virtual humans). When two interac-
tants have similar understanding of what the speaker says, their non-verbal behaviours
appear synchronous. Conversely, when the two partners have different understanding of
what is being said, they disynchronise. This model is implemented as a dynamical cou-
pling between two talking agents: on one hand, each agent proposes its own dynamics;
on the other hand, each agent is influenced by its perception of the other. These are the
two minimal conditions enabling coupling. What makes this model particular is that the
internal dynamics of agents are generated by the meaning exchanged through speech. It
links the dynamical side of interaction to the formal side of speech.
We tested this model in simulation, and showed that synchrony effectively emerges
between agents when they have close level of understanding. We noticed a clear effect
of the level of understanding on the capacity of the agents to both remain synchronous
and re-synchronise: agents disynchronise if the level of shared understanding is lower
than
85%
(with our parameters) and conversely agents synchronise if the level of shared
understanding is higher than
85%
. These results tend to prove that, considering that syn-
chrony between agents is an indice of good interaction and shared understanding, the
reciprocal property is true too; that is disynchrony accounts for misunderstanding.
We have shown that agents remain synchronous depends on both their shared un-
derstanding (the ratio between
u
1
and
u
2
) and their sensitivity to non-verbal behaviour
(
σ
in our implementation). The more sensitive to non-verbal behaviours are the agents,
the more resistant to disynchronisation is the dyad and the easier is the synchronisation.
