We present a model that explores the influence of persuasion in a population
of agents with positive and negative opinion orientations. The opinion of each
agent is represented by an integer number k that expresses its level of
agreement on a given issue, from totally against k=−M to totally in favor
k=M. Same-orientation agents persuade each other with probability p,
becoming more extreme, while opposite-orientation agents become more moderate
as they reach a compromise with probability q. The population initially
evolves to (a) a polarized state for r=p/q>1, where opinions' distribution is
peaked at the extreme values k=±M, or (b) a centralized state for r<1,
with most opinions around k=±1. When r≫1, polarization lasts for a
time that diverges as rMlnN, where N is the population's size. Finally,
an extremist consensus (k=M or −M) is reached in a time that scales as
r−1 for r≪1