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reached after 150 ticks and sustained until the end of the simulation. In contrast, for
the moderate social conformity preference mobilisation proceeds slower but continu-
ously improves towards the end of the simulation. This slow-down of social mobilisa-
tion may be attributed to an on-going process of social adjustment: Clearly, compared
to the first diagram of Fig. 1, the achieved social conformity does not drop as steeply
and instead continues to increase during the simulation after tick 100. Likewise, for
the medium social conformity setting we observe a decrease of the standard deviation
of the contributions (dashed black) which does not occur for the low social confor-
mity setting. An additional difference between simulations with low and medium
settings for the social conformity preference lies in the development of the behav-
ioural stability indicator (delta contribution in blue) that reflects the individual change
in behaviour between two consecutive simulation ticks: While under both settings
contributions settle around a mean of 0.3, in the absence of social conformity prefer-
ences individual behaviours appear to fluctuate significantly (around 0.1) from one
tick to the next throughout the simulation, i.e. agents continuously adjust their behav-
iour. With medium social conformity preference this effect is dampened and delta
contribution approaches zero over time. Apparently, the striving for social conformity
not only decreases the spread of behaviours within the population; it also decreases
the spread of behaviours selected by one agent over time. The following section goes
a step further and reports on simulation results for agent populations with heterogene-
ous preference profiles.
4.3
Social Influence in Heterogeneous Populations
This section investigates the interplay between social conformity and social orienta-
tions in heterogeneous agent populations. We set up populations with different ratios
of altruistic agents and egoistic agents, and different (population) global settings of
the social conformity preference. The investigated parameter combinations are docu-
mented in Table 2. Again, for each population composition and parameter settings 20
independent runs over 400 steps are performed.
Table 2.
Agent types, respective preference sets and population composition used in the
sensitivity analysis. Two basic types of agents regarding social orientation are investigated. For
each basic type three different settings for the social conformity preference are considered. For
each preference set a total of 9 population compositions is investigated.
socialConformityPreference
Proportion of agents in population
Altruists 0.1, 0.2,…, 0.9
Egoists
1 - proportion of altruists
Results are reported with respect to the following extension of three of the
performance indicators introduced in the previous section:
0.0, 0.1, and 0.2
•
Agents' behaviours in terms of their mean contribution (black), mean contributions
of altruistic agents (dashed black), and mean contributions of egoistic agents
(dotted black).
