  We study the effects of bounded confidence thresholds and of interaction and
external noise on Axelrod's model of social influence. Our study is based on a
combination of numerical simulations and an integration of the mean-field
Master equation describing the system in the thermodynamic limit. We find that
interaction thresholds affect the system only quantitatively, but that they do
not alter the basic phase structure. The known crossover between an ordered and
a disordered state in finite systems subject to external noise persists in
models with general confidence threshold. Interaction noise here facilitates
the dynamics and reduces relaxation times. We also study Axelrod systems with
metric features, and point out similarities and differences compared to models
with nominal features. Metric features are used to demonstrate that a small
group of extremists can have a significant impact on the opinion dynamics of a
population of Axelrod agents.
